Key Messages

• We conducted a Health Technology Assessment (HTA) to inform decisions related to the adoption, implementation, and evaluation of peer support programs for youth mental health. This HTA consisted of consultations with youth advisors (peer support users and workers), a systematic review of the available evidence on the clinical effectiveness and safety of peer support interventions for youth with mental health concerns (compared with interventions without peer support), and an Environmental Scan of peer support program evaluations.
• Youth recognize the value of peer support in their mental health recovery and wellness, and they view peer support as an accessible, convenient, and safe mental health resource. They also highlight the importance of representation and involvement of youth with diverse backgrounds and experiences across the design and evaluation of peer support programs to ensure equity, diversity, and inclusion.
• In the Clinical Review, we found that formal peer support programs (i.e., trained peer support workers based at structured community- or health clinic–based organizations provide support to peer support users) might help a young person feel more comfortable to share information about their mental health issue and ask for help. The authors of 2 randomized controlled trials we identified found that compared to no peer support, peer support may improve youth’s attitudes toward disclosure of mental illness, distress related to that disclosure, and help-seeking behaviour. However, overall, only a small amount of low-quality evidence (due to risk of bias, inconsistency, indirectness, and imprecision) is available. Therefore, it is very uncertain whether peer support programs are more effective at supporting an individual in their recovery compared to programs without a peer support component. In addition, the safety of peer support programs is currently unknown (no research evidence was found).
• Our Environmental Scan did not identify formal guidelines or best practices for evaluating peer support programs; however, we found some common evaluation approaches among programs. These approaches include focusing on recovery-oriented outcomes, involving youth throughout the evaluation (to ensure relevance), and tailoring the evaluation to reflect the local program context.
• When considering implementation of peer support programs for youth mental health, decision-makers may wish to allocate resources for ongoing program evaluation. Strengthened program evaluations can improve the understanding of the benefits and maximize the effectiveness of peer support programs. In addition, practice-based evidence from the evaluation of peer support programs can be used to further support the design and implementation of appropriate, equitable, and culturally competent programs.

Summary

Introduction

Context and Decision Problems

Peer Support Youth Advisor Engagement

Results

The reporting of this section follows the GRIPP2 Short Form¹⁹ reporting checklist and includes the results, discussion, and reflections and critical perspectives on advisor involvement, to outline the process of engagement and where and how advisors’ contributions were used in the review.

Table 1

Peer Support Youth Advisor Involvement in CADTH’s Health Technology Review of Peer Support Programs for Youth Mental Health.

Systematic Review of Clinical Effectiveness and Safety

Methods

Review Conduct

For the current SR, we followed a protocol that was written a priori. We prospectively registered the protocol for the Clinical Review in the international repository PROSPERO (registration number: CRD42022299556). We made no protocol amendments during the review. We have reported the Clinical Review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 statement.³⁰

Literature Search Strategy

The literature search for clinical studies was performed by an information specialist using a peer-reviewed search strategy according to the PRESS Peer Review of Electronic Search Strategies checklist.³¹ The complete search strategy is presented in Appendix 1.

Published literature was identified by searching the following bibliographic databases: MEDLINE All (1946‒) via Ovid, Embase (1974‒) via Ovid, the Cumulative Index to Nursing and Allied Health Literature (CINAHL) via EBSCO, PsycInfo via Ovid, Cochrane Central Register of Controlled Trials via Ovid, and Scopus. All Ovid searches, with the exception of Cochrane Central Register of Controlled Trials, were run simultaneously as a multi-file search. Duplicates were removed using Ovid deduplication for multi-file searches, followed by manual deduplication in Endnote. The search strategy comprised both controlled vocabulary, such as the National Library of Medicine’s MeSH (Medical Subject Headings), and keywords. The main search concepts were peer support and youth with mental health concerns. Clinical trials registries searched were the US National Institutes of Health’s clinicaltrials.gov, WHO’s International Clinical Trials Registry Platform (ICTRP) search portal, Health Canada’s Clinical Trials Database, and the European Union Clinical Trials Register.

CADTH-developed search filters were applied to limit retrieval to health technology assessments, systematic reviews, meta-analyses, or network meta-analyses, and any types of clinical trials or observational studies. The search was limited to English- and French-language documents published between January 1, 2006, and December 17, 2021. Conference abstracts were excluded from the search results.

Regular alerts updated the database literature searches until the publication of the final report. The clinical trials registries search was updated before the completion of the stakeholder feedback period.

Grey literature (literature that is not commercially published) was identified by searching sources listed in relevant sections of the Grey Matters: A Practical Tool For Searching Health-Related Grey Literature checklist,³² which includes the websites of regulatory agencies, HTA agencies, clinical guideline repositories, systematic review repositories, patient-related groups, and professional associations. Google was used to search for additional internet-based materials. These searches were supplemented by reviewing bibliographies of key papers (relevant SRs and the included primary studies) and through contacts with experts and industry, as appropriate. The grey literature search was updated before the completion of the stakeholder feedback period. See Appendix 1 for more information on the grey literature search strategy.

Study Eligibility Criteria

Table 2 shows the study eligibility criteria for the clinical research questions.

Screening and Selecting Studies for Inclusion

We considered the following criteria when selecting studies for inclusion:

• For this review, youth were defined as individuals aged between 12 and 25 years because this age range overlaps with that of youth mental health hubs (which often include peer support) in several Canadian provinces and the time period when mental health concerns often first appear.³⁶
• Youth could be of any gender, sexuality, or ethnicity. Studies in all settings were eligible for inclusion. There were no restrictions placed on setting or severity of symptoms.
• Studies of wider populations (i.e., including children and/or adults) were included if:
  • findings for youth could be isolated (e.g., in subgroup analyses)
  • at least 80% of the sample consisted of youth
  • the mean and mean ± 1.5 standard deviation (SD) age fell between 12 and 25 years.
• Peer support workers could be of any age.

Table 2

Selection Criteria for Clinical Research Questions.

• Peer support could be offered on a one-to-one or on a group basis, be in person or virtual (e.g., video or telephone chat), and synchronous (in real time; e.g., in-person sessions, video chat) or asynchronous (not in real time; e.g., text messaging).
• Mental health concerns could be of any severity.
• Studies that had a larger scope than only youth with mental health concerns (e.g., studies of youth with both mental health concerns and substance use disorders) were included if relevant findings related to peer support primarily for mental health concerns were reported in isolation (e.g., in a subgroup).
• Peer service users could receive concurrent interventions (e.g., psychotherapy, pharmacotherapy).
• For the outcomes, all instruments and all time points were eligible for inclusion.
• Studies not meeting the eligibility criteria outlined in Table 2 or published in a language other than English or French were excluded.

Study Selection

Two reviewers independently screened titles and abstracts for relevance to the clinical research questions following the liberal accelerated approach (i.e., a single reviewer’s decision was required for inclusion, and 2 reviewers’ decisions for exclusion).^37,38 We retrieved full-text articles that at least 1 reviewer judged to be potentially relevant and independently assessed these for possible inclusion based on the predetermined selection criteria (Table 2). We used Distiller SR (Evidence Partners, Ottawa, Canada) to facilitate study selection. One reviewer scanned the reference lists of the included studies and relevant SRs to locate additional studies of potential interest. Two reviewers independently reviewed full text of all selected articles. The 2 reviewers compared their chosen included and excluded studies and discussed disagreements until consensus was reached, involving the opinion of a third reviewer, if needed (i.e., methodologist, content expert). We presented the study selection process in a flow chart. We had planned to contact study authors if any additional information was needed to determine the relevancy of any studies. However, this ended up not being necessary. We posted a list of studies selected for inclusion in the Clinical Review to the CADTH website for stakeholder review and feedback for 10 business days and planned to review any additional studies identified for potential inclusion. No additional studies were identified. We screened studies identified through search alerts using the aforementioned process and incorporated those meeting the selection criteria of the review into the analysis if they were identified before the end of the stakeholder feedback period for the draft report. We had planned to describe studies identified after the last stakeholder feedback period in the discussion, with a focus on comparing their results with those obtained from the synthesis of earlier reports included in the review. However, no additional studies were identified after stakeholder feedback period.

Data Extraction

A single reviewer performed data extraction with independent verification for accuracy and completeness by a second reviewer. Reviewers extracted data directly into Microsoft Office Word. Because there were only 2 included studies, we deemed it not possible to truly pilot the form, and instead edited it iteratively as needed. The information extracted included characteristics of the study (i.e., design, setting, funding source), population (i.e., inclusion and exclusion criteria, number of participants, age, sex and/or gender, sexuality, race and/or ethnicity, mental health concerns), intervention (i.e., details of the program, number of sessions, selection and training of peer supporters) and comparators, outcomes and their ascertainment (e.g., instruments used for measurement), length of follow-up and time points of outcome measurement, and results data regarding the outcomes and the subgroups of interest. Because 1 of the included trials was published in 2 reports, we extracted data from the main publication (Conley et al.)³⁹ and only additional information and any data related to the 2-month follow-up were extracted from Hundert et al.⁴⁰

We extracted all data that were compatible with each relevant outcome domain at any duration of follow-up, including measures of treatment effects (e.g., mean changes in outcome scores from baseline to follow-up), and any results of between-group statistical tests reported on those measures. We made no assumptions about the presence or absence of an outcome if it was not reported in the study. For example, we did not assume that no adverse events occurred only because the authors did not report on any. We did not make any attempts to contact study authors because we did not deem any relevant data to be unclear or missing.

Risk-of-Bias Appraisal

Two independent reviewers assessed outcome-level risk of bias (or for groups of outcomes believed to be at similar risk of bias, for feasibility reasons) of RCTs from the intention-to-treat perspective using version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2).⁴¹ Because there were only 2 included studies, we did not pilot the RoB form. The RoB 2 assessment tool is structured into 5 domains to assist in evaluating biases arising from the randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result.⁴¹ For each domain, we assigned a judgment of low risk of bias, high risk of bias, or some concerns about risk of bias. We then judged the overall risk of bias of each trial as low risk of bias, some concerns about risk of bias, or high risk of bias based on the domain-level determinations. We predicted the direction of the potential risk of bias when possible and provided a rationale for decisions about the risk of bias for both the domain-level and overall assessments.

Reviewers resolved disagreements in the risk of bias for the domain-level and overall assessments through discussion. We did not exclude studies from the review based on the results of the critical appraisal. However, we incorporated the critical appraisal results into assessments of the certainty in the body of evidence for each outcome comparison.

Data Analysis and Synthesis

Narrative Synthesis

We considered factors such as clinical heterogeneity (i.e., differences in study setting, populations, and interventions), methodological heterogeneity across the included trials, and the reported outcome measures in our decision on whether to pool findings statistically via a meta-analysis. Because we included only 2 trials in this review and many of the outcomes were reported by a single trial, it did not seem appropriate nor informative to conduct a statistical synthesis. Instead, we conducted a narrative synthesis of the results reported in the trials considering available guidance.⁴² The narrative synthesis included the presentation of study characteristics and findings by outcome within summary tables, together with descriptions in the main text. To synthesize study findings, we first grouped trials by outcome domain and time point of interest for the comparisons between peer support interventions and control groups. We then developed a preliminary synthesis by organizing the findings and identifying patterns in the size and direction of reported effects. We evaluated the within and between-study relationships and discussed the findings about the direction and magnitude of any observed effects. We interpreted the findings with consideration for the differences in instruments used across the studies. We chose to synthesize data at the 3 reported time points; namely, post-intervention, post-booster (available in 1 study), and at the longest follow-up. We considered the sample size of the included trials and their risk of bias in determining the relative weight of each study’s findings in the overall conclusion. However, the included studies were both similar in sample size (both small, N < 120) and had high risk of bias; therefore, their findings were considered to contribute equally to the overall conclusion. Reviewers then came to consensus on having a single overall conclusion across trials for each outcome comparison (i.e., favouring either intervention or comparator, little to no difference).

When findings across the trials were heterogeneous (especially in terms of direction of observed effects), we had planned to explore this heterogeneity using within- and between-study subgroup analyses. No within-study subgroup analyses were reported in the included trials, and the small number of trials representing various subgroups precluded drawing credible conclusions about the potential sources of heterogeneity. Therefore, we drew conclusions based on the main comparison and did not present separate conclusions by subgroups of the population or intervention. Instead, we considered this unexplained heterogeneity in our assessments of the certainty of the evidence.

We had planned to assess the risk of small study bias for meta-analyses containing at least 10 studies of variable size,⁴³ but because we only included 2 trials and did not perform a meta-analysis, we were unable to complete this assessment.

Certainty of the Evidence

Two independent reviewers rated the certainty of the body of evidence for each outcome comparison using the methods of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group.^44,45 Reviewers discussed discrepancies until consensus was reached. We had planned to contact study authors if any additional information was needed to complete the GRADE assessments; however, this did not end up being necessary.

Following the GRADE approach, the included RCTs started as high certainty evidence.^45,46 We then rated down the certainty in treatment effect estimates for concerns related to risk of bias, inconsistency across studies, indirectness, imprecision of effects, and/or publication bias.^45,46 We considered the possibility of rating up the certainty of evidence, but this was not appropriate for any outcome comparison.^45,46 Ultimately, the GRADE approach resulted in an assessment of the certainty of a body of evidence in 1 of 4 grades: high, moderate, low, or very low.⁴⁷ Because the certainty in the evidence decreased, so did our confidence that the estimate of effect from the included study was close to that of the true effect.⁴⁷ We employed a non-contextualized approach whereby we rated the certainty that a non-null effect was present.⁴⁸

The results of GRADE assessments are reported in the Summary of Findings tables in Appendix 2, which include notes that justify all decisions to rate down the certainty of the evidence for any given outcome comparison. When providing summaries of the evidence in the text, we used the word “may” for low certainty evidence and “probably” or “likely” for moderate certainty evidence.⁴⁹ We describe very low certainty evidence as “very uncertain.”⁴⁹

Results

Quantity of Research Available

We identified 5,357 unique citations via the electronic literature search. We excluded 5,168 of these records during title and abstract screening. We retrieved 8 additional records from the grey literature search. After full-text screening of 197 potentially relevant articles, we excluded 194 records and included 3 publications^39,40,50 (reporting results from 2 RCTs). No additional unique studies were identified during the stakeholder review of the included studies nor from subsequent search alerts. A PRISMA flow chart³⁰ (Appendix 2, Figure 1) shows the study selection process. We have included a list of excluded studies with the reason for exclusion in Appendix 3.

Trial and Participant Characteristics

We identified 2 open-label RCTs (reported in 3 publications)^39,40,50 that were included in this Clinical Review. Conley et al. (2020)³⁹ evaluated a peer support program among students from 3 university campuses in the US. A second publication,⁴⁰ about the same trial (Hundert et al. [2021]) reported results from a subset of participants who were followed for a longer period. Mulfinger et al. (2018)⁵⁰ assessed the effectiveness of a peer support intervention among adolescent psychiatric patients in Germany. Table 3 shows the overview of characteristics of the included trials. We have included a detailed table of characteristics of the included trials in Table 8 (Appendix 2). Throughout this report, we have used the term “mental health concerns” to denote self-reported or formally diagnosed mental health concerns. However, if the included studies used the term “mental illness” to describe the study population, we retained that terminology.

Table 3

Overview of Characteristics of Included Clinical Trials.

Population

In the study by Conley et al.,³⁹ university students (aged ≥ 18 years) with a self-identified mental health challenge or mental illness were included. The study by Mulfinger et al.⁵⁰ included adolescent psychiatric patients aged 13 to 18 years with at least 1 self-reported current axis I or axis II disorder (e.g., psychiatric illnesses such as anxiety, depression; personality disorders), and a moderate (or severe) level of self-reported disclosure-related distress. Across the trials, 216 participants were included (Conley et al.,³⁹ N = 118; Mulfinger et al.,⁵⁰ N = 98). Across the studies, depressive symptoms were reported in 59.1%⁵⁰ to 85.5%³⁹ of participants, while 17.3%⁵⁰ to 69.2%³⁹ reported anxiety symptoms. The authors did not describe other mental health concerns potentially experienced by participants. The population in the trial by Conley et al.³⁹ was mostly female (82.2%), White (68.6%) and heterosexual (66.9%). In the Mulfinger et al. study,⁵⁰ most participants were female (69.3%), born in Germany (94.8%), and with a mean of 22.5 (SD = 32.2) months since their first psychiatric diagnosis.

Intervention and Comparators

The peer support intervention in both of the included trials^39,50 was the Honest, Open, Proud (HOP) program.⁵¹ HOP was a peer-led, in-person group intervention developed to empower participants with disclosing their mental health concerns and to reduce their mental health-related self-stigma. HOP was originally developed for adults but was later adapted for adolescents. This manualized program covered 5 themes in three 2-hour sessions over the course of 3 weeks. These included beliefs and attitudes about having a mental illness, the advantages and disadvantages of disclosing one’s mental illness, recognizing the right people and setting for disclosure, personal disclosure and telling one’s own story, and about the role of solidarity and peer support. The sessions included vignettes, role plays, exercises on self-reflection, and group discussions. Conley et al.³⁹ evaluated the college version of HOP (HOP-C), which was adapted for university students. In the HOP-C program, the first session included a discussion on the concepts of identifying as an individual with mental illness and the pros and cons of disclosure. In the second session, different ways of disclosure, including social media disclosure, were discussed; in the third session, participants were asked to craft personal disclosure stories and to practice telling their story. The HOP-C program included an additional booster workshop session given 2 to 3 weeks later.³⁹ The session manual and a workbook for the participants are available online.^51,52

The sessions were led by trained individuals who had shared lived experience of mental illness. The peer facilitators were youth or young adults who underwent a 2-day training course. In the Mulfinger et al. study, a young mental health professional was also present for the sessions.⁵⁰ Because this study was conducted in Germany, the program was adapted to a German context.

The comparators were treatment as usual (TAU)⁵⁰ or a waitlist control.^39,40 In the Mulfinger et al. study, participants in both groups received TAU, which included regular care from the psychiatric clinic.⁵⁰ Additional details of usual treatment were unclear from the publication. In the Conley et al. study, HOP-C was compared with a waitlist control group, who were offered the program at a later point in time. In the HOP-C group, 41.3% (n = 26) of participants were reported as receiving therapy or counselling and 57.1% (n = 36) were reported as receiving medications at the time of the study; 45.5% (n = 25) and 54.5% (n = 30) of participants in the waitlist group were reported as receiving therapy or counselling and medications, respectively, at the time of the study.^39,40

Outcomes

The included trials assessed several self-reported outcomes, mostly related to personal recovery. Among them, self-stigma and stigma stress were reported in both included trials.^39,40,50 Other personal recovery outcomes, such as secrecy and disclosing mental illness (e.g., self-efficacy about disclosing mental illness, attitudes to disclosure), health-related quality of life (HRQoL), self-identified stage of recovery, empowerment, feelings of hopelessness, social withdrawal, and help-seeking, were included only in the Mulfinger et al. trial.⁵⁰ Clinical outcomes, such as symptoms of anxiety (Conley et al.)^39,40 and depression (both trials),^39,40,50 were included. No outcomes related to health care resource utilization or social outcomes were reported. Detailed descriptions of all outcome measures are available in Table 33 in Appendix 2. No relevant studies were identified that reported on harms related to peer support. The authors of the included studies did not report on the safety of peer support workers.

Both trials measured the outcomes at baseline, after the HOP sessions (post-intervention), and at follow-up.^39,50 The follow-up time ranged from 6 weeks after baseline (3 weeks after the sessions) in the Conley et al. trial³⁹ to around 2 months after the sessions (5 weeks after booster) in the Mulfinger et al. trial.⁵⁰ In the Conley et al. trial, the intervention included an additional booster session 3 weeks after completion of the initial program; an additional outcome assessment was conducted after this booster session (post-booster).³⁹

Risk-of-Bias Appraisal

Table 4 shows a summary of the risk-of-bias assessments for the 2 RCTs.^39,40,50 Table 9 in Appendix 2 shows the detailed risk-of-bias assessments. Overall, we assessed the included RCTs to have a high risk of bias.

Table 4

Risk of Bias Summary — RCTs (RoB 2, Effect of Assignment to the Intervention).

For the risk of bias arising from the randomization process, we judged the Conley et al. study^39,40 to have some concerns because the randomization method at 1 site may not have been adequate. While 2 universities appeared to have used adequate randomization methodologies, a third used “blindly shuffled pieces of paper”; this methodology may not have been adequate and it is possible that the allocation of participants was revealed before their assignment to treatment groups.^39,40 The magnitude and direction of bias this may have been introduced is not clear. There were no serious concerns about risk of bias due to deviation from the intended interventions. All outcomes reported in both RCTs^39,40,50 were at a high risk of bias due to missing outcome data. In the Conley et al. study, data from up to 33% of participants in the HOP group and 19% of in the control group were missing at the longest follow-up; it is possible that the high and imbalanced losses to follow-up were at least in part related to perceived lack of efficacy in the HOP group. There was also no evidence to indicate that the results were not biased by missing outcome data (e.g., sensitivity analyses). Similarly, in the Mulfinger et al. study, data from 22% of participants were missing in both groups.⁵⁰ We also judged both RCTs^39,40,50 to be at a high risk of bias in measurement of the outcome because all outcomes were self-reported by the study participants who were aware of their treatment allocation, and it was possible that this knowledge influenced the outcome assessment. Although it is possible that response of participants in both groups were influenced by their allocation, it is likely that this risk favoured the intervention (HOP or HOP-C) because it is possible that the participants assigned to the intervention group might have been optimistic of the effects of the intervention. Published protocols were not available for either of the studies; therefore, it was unclear if data for all outcomes were analyzed in accordance with a pre-specified analysis plan that was finalized before unblinding of outcome data. However, the Mulfinger et al. study⁵⁰ was registered (NCT02751229) and all reported outcomes were pre-specified. The predicted direction of the risk of potential bias in selection of the reported result is unclear for both trials.

Data Analysis and Synthesis

Table 5 shows a high-level overview of the findings and certainty of evidence assessments for each outcome comparing the clinical effectiveness of peer support programs versus interventions without peer support (i.e., waitlist or TAU) for the management of mental health concerns among youth. Appendix 2 presents detailed GRADE Summary of Findings tables which include notes that detail the reasons for rating down the certainty of evidence. We identified no relevant studies regarding the safety of peer support programs compared with interventions without peer support.

Table 5

High-Level Overview of Trial Findings and GRADE Assessments.

Question 1: Clinical Effectiveness

In this section, we present the findings for all the outcomes on the clinical effectiveness of peer support interventions from the included trials. Overall, we judged the certainty of the evidence regarding the clinical effectiveness of peer support programs compared with interventions without peer support on all outcomes across all time points to be very uncertain due to serious concerns across all GRADE domains aside from publication bias: risk of bias, inconsistency, indirectness, and imprecision. Therefore, readers should be mindful when interpreting the results that the true effect of formal peer support programs compared with interventions without peer support may be very different than the findings generated from these 2 trials. The trials were judged to be at high risk of bias due to missing outcome data and self-reported subjective outcomes that may have been affected by the open-label nature of the trials. We rated down our certainty in the evidence due to serious concerns about inconsistency because either only 1 trial was available that reported on the outcome (limited evidence of consistency) or because of inconsistent results between the trials (at post-intervention). We judged the results to be indirect because the effect of the single included intervention (HOP or HOP-C) is unlikely to be representative of the wide spectrum of peer-support interventions that may exist for all youth (including populations that are disadvantaged) across the spectrum of mental health concerns. We also assessed the evidence as imprecise because of the small sample size in each comparison (n < 400), which may have resulted in unstable estimates of effect. Although only 2 trials were included, we did not find any persuasive evidence of publication bias; instead, we consider it quite possible that many programs exist but are not formally evaluated and shared in the public domain. Therefore, we did not rate down in that domain for any outcome comparison.

Stigma

Self-Stigma

The authors of the 2 RCTs (in 3 publications)^39,40,50 reported on self-stigma or internalized stigma. The peer support interventions were the HOP⁵⁰ and HOP-C^39,40 programs, which were compared with TAU⁵⁰ or waitlist controls.^39,40 Outcomes were measured at post-intervention, post-booster, and at follow-up (6 weeks⁵⁰ or 2 months⁴⁰ after core sessions) using the 4 subscales of the Self-Stigma of Mental Illness Scale–Short Form (SSMIS-SF; range = 5 to 45)⁵³ or the Internalized Stigma of Mental Illness scale⁵⁴ (10-item version, range = 1 to 4). Conley et al.^39,40 reported the mean score from 3 subscales of the SSMIS-S ranging from 1 to 5 for each subscale. For both measures, higher scores indicate more self-stigma.

At post-intervention, the results were heterogenous (2 RCTs,^39,50 N = 191) and we consider the findings to be very uncertain. Conley et al.³⁹ found that in the harm subdomain of the SSMIS-SF scale, HOP-C was favoured compared with waitlist control at follow-up. The mean scores of the harm subdomain in the HOP group were 3.23 (SD = 2.08) at baseline and 2.49 (SD = 1.65) at post-intervention, whereas the scores in the waitlist control were 2.92 (SD = 1.75) at baseline and 3.02 (SD = 2.08) at post-intervention (P = 0.019).³⁹ The authors did not report results for change from baseline for the other domains. In the Mulfinger et al. study, at post-intervention, change from baseline of the overall score of SSMIS showed that HOP was associated with a reduction in self-stigma compared with TAU (mean between-group difference for change from baseline = –2.93; 95% CI, –5.35 to –0.52). There was no significant difference between groups in the change from baseline of ISMI scores.⁵⁰

At post-booster (1 RCT,³⁹ N = 97), evidence from the study by Conley et al. showed little to no difference in the effect of HOP-C compared to waitlist in reducing self-stigma, as found by between-group t-tests for the agreement, application, and harm subdomains of the SSMIS-SF. However, we consider these findings to be very uncertain, and we could not rule out an effect in either direction because the apparent lack of difference could be related to imprecision resulting from the small sample size.

At the longest follow-up (2 RCTs, N = 117; 6 weeks⁵⁰ or 2 months⁴⁰), the evidence was heterogenous, and we consider the findings very uncertain. HOP-C was not associated with any significant reduction in any of the subdomain scores of SSMIS compared with waitlist control. Results from the study by Mulfinger et al.⁵⁰ found that participants who received HOP reported lower self-stigma scores at 2 months follow-up compared with those who received TAU. The mean between-group difference for change from baseline in ISMI scores was –0.35 (95% CI, –0.54 to –0.05); the mean between-group difference for change from baseline in SSMIS scores was –5.14 (95% C, –8.22 to –2.05).

Stigma Stress

Both included RCTs^39,40,50 reported on stigma stress. Outcomes were measured at post-intervention and at follow-up (6 weeks⁵⁰ to 2 months⁴⁰ after core sessions). In the HOP trial and in the 2-month follow-up of the HOP-C trial, the Stigma Stress Scale (score range, –6 to 6) was used to calculate stigma stress as perceived harm minus perceived resources. Higher scores indicated increased stigma-related stress. At the post-intervention and post-booster follow-ups of the HOP-C trial, stigma stress was not calculated; rather, the results of the subscale scores were reported separately.

At post-intervention, Mulfinger and colleagues⁵⁰ (N = 84) reported that peer support may be favoured compared with TAU in lowering the stress related to self-stigma. The mean between-group difference for change from baseline to post-intervention was –2.06 (95% CI, –2.70 to –1.42), but we consider the evidence to be very uncertain..⁵⁰

At the longest follow-up, the evidence was heterogenous (2 RCTs, N = 117^40,50; 6 weeks⁵⁰ or 2 months⁴⁰) and we consider the overall certainty of the evidence to be very low. The Conley et al. trial (reported in Hundert et al.)⁴⁰ showed there was little to no difference (potentially related to imprecision) in the effect of peer support intervention (HOP-C) in reducing stigma-related stress, whereas the results from the Mulfinger et al. trial⁵⁰ favoured peer support. At 6 weeks follow-up, the mean difference for change in scores from baseline in the HOP group was 2.19 units lower than the TAU group (95% CI, –2.89 to –1.43). At post-intervention and at post-booster, Conley et al.³⁹ found that there was a significant increase in the scores related to perceived resources to cope with stigma stress in the HOP-C group compared with the control group (P = 0.001). There were no differences in the subscale stigma as a stressor (perceived harm). However, the stigma stress scores were not calculated for post-intervention and post-booster time points.

Secrecy and Disclosing Mental Illness

Self-Efficacy Related to Secrecy and Disclosing of Mental Illness

The HOP-C trial by Conley et al.^39,40 reported on participants’ self-reported self-efficacy related to secrecy and to the disclosure of mental illness. The outcome was assessed by 2 questions: “How confident are you in making decisions and handling well all the issues related to disclosing your mental illness? (p.171)”³⁹ and “How confident are you in making decisions and handling well all the issues related to keeping mental illness a secret?” Answers were rated from 1 (not at all) to 7 (very much).

At post-intervention, there was little to no difference (potentially due to imprecision) in the effect of peer support in efficacy related to keeping the mental illness a secret or to that related to disclosure of mental illness compared with no peer support (n = 107)³⁹ Following a booster session (n = 97), the trial showed that HOP may be favoured with respect to self-efficacy about disclosure (P = 0.001) but there may be little to no difference in self-efficacy related to keeping mental illness a secret.³⁹ At the 2 month follow-up assessment (n = 55), the results suggested that there may be little to no difference in the effect of peer support versus no peer support (waitlist) in self-efficacy related to secrecy or to disclosing mental illness.⁴⁰ We considered the evidence at all time points to be very uncertain.

Attitudes to Disclosure

Mulfinger et al.⁵⁰ reported on participants’ attitude to disclosure of mental illness to family and friends and to teachers and employers. The outcome was assessed by 2 questions about how comfortable they are in disclosing mental illness to family and friends, and teachers and employers. Answers were rated from 1 (not at all) to 7 (very much).

The trial showed that peer support may be favoured compared to TAU on improving the attitudes of participants to disclosing their mental illness at post-intervention and at 6 weeks follow-up, but we considered the evidence informing these results to be very uncertain. At post-intervention (n = 84), participants in the HOP group reported significantly higher improvement from baseline in their attitudes to disclosure toward family and friends (mean between-group difference for change from baseline = 1.00; 95% CI, 0.43 to 1.57) and toward teachers and employers (mean between-group difference for change from baseline = 0.66; 95% CI, 0.15 to 1.16) compared with participants in the TAU group. Similarly, at the 6-week follow-up assessment (n = 62), participants in the HOP group reported significantly higher improvement from baseline in their attitudes to disclosure toward family and friends (mean between-group difference for change from baseline = 1.02; 95% CI, 0.43 to 1.61) and toward teachers and employers (mean between-group difference for change from baseline = 0.91; 95% CI, 0.28 to 1.53) compared with participants in the TAU group, but we considered the evidence to be very uncertain.

Disclosure-Related Distress

Mulfinger et al.⁵⁰ reported on participants’ distress related to disclosure of mental illness. The outcome was assessed by a single question about how distressed or worried participants were about disclosing mental illness. Answers were rated from 1 (not at all) to 7 (very much). This single item was also used as a screening item for study inclusion, with a score of 4 or higher required to be enrolled to the trial.

The results of the trial showed that peer support may be favoured over TAU for lowering participants’ disclosure-related distress at post-intervention and at the 6-week follow-up, but we consider this evidence to be very uncertain. At post-intervention (n = 84), the between-group difference for change from baseline was –0.44 (95% CI, –0.79 to –0.08). Similarly, at the 6-week follow-up (n = 62), the distress related to disclosure of mental illness was lower in the HOP group compared with the TAU group (mean between-group difference for change from baseline = –0.78; 95% CI, –1.16 to –0.40).

Secrecy

Mulfinger et al.⁵⁰ reported on participants’ secrecy related to mental illness. The outcome was assessed by the Stigma Coping and Orientation subscale of the Link Stigma Scale.⁵⁵ Higher mean scores (range = 1 to 6) indicate more secrecy.⁵⁰

The results of the trial showed that peer support may be favoured compared with TAU on lowering the participants’ secrecy related to mental illness at post-treatment, and at 6 weeks follow-up, but we considered the evidence to be very uncertain. At post-intervention (n = 84) and at 6-week follow-up (n = 62), the mean between-group differences of change from baseline were –0.44 (95% CI, –0.79 to –0.08), and –0.78 (95% CI, –1.16 to –0.40), respectively.

Health-Related Quality of Life

Mulfinger et al.⁵⁰ reported on participants’ HRQoL. The outcome was assessed by KIDSCREEN-10,⁵⁶ a 10-item questionnaire with a total score range from 10 to 50, with higher scores indicating better quality of life.^56,57

The results from the trial showed that at post-intervention (n = 84) there may be little to no difference in the effect of peer support on HRQoL compared to TAU, but we considered the evidence to be very uncertain, and could not rule out the potential for a difference between groups due to imprecision. At the 6-week follow-up assessment (n = 62), the results suggested that HOP may be favoured compared to TAU in improving HRQoL, but we considered the evidence to be very uncertain. The mean between-group difference in score for change from baseline to 6-week follow-up was 3.54 (95% CI, 1.14 to 5.93).

Empowerment

Mulfinger et al.⁵⁰ reported on participants’ feeling of empowerment. The outcome was assessed by the Self-esteem (9 items) and Optimism (4 items) subscales of the Empowerment Scale.⁵⁸ A mean score was calculated from the scores of each of the subscales (range = 1 to 4), with higher scores indicating more empowerment.

In the self-esteem subscale of the Empowerment Scale, the results from the trial showed that at post-intervention (n = 84), participants in the HOP group reported a larger improvement in self-esteem compared with those in the TAU group (mean between-group differences for change from baseline = 0.21; 95% CI, 0.04 to 0.39). At 6-week follow-up (n = 62) there was no significant difference between the groups. In the optimism subscale, the results showed that there was no significant difference between the groups at post-intervention or at 6-week follow-up. Overall, we concluded that there may be little to no difference in the effect of peer support on feeling of empowerment compared to TAU at all time points; however, we considered the evidence to be of very low certainty.

Social Withdrawal

Mulfinger et al.⁵⁰ reported on participants’ self-reported assessment of social withdrawal. The outcome was assessed by the Stigma Coping Orientation subscale of the Link Stigma Scale⁵⁵ (7 items related to withdrawal). Higher mean scores (range = 1 to 6) indicate more social withdrawal.⁵⁰

The results of the trial suggested that peer support may be favoured compared with TAU on lowering the participants’ social withdrawal at post-intervention, but the evidence was very uncertain (mean between-group difference for change from baseline = 0.34; 95% CI, –0.63 to –0.05; n = 84). At 6 weeks post-intervention (n = 62), there was no significant difference between the groups in the change from baseline of mean scores; however, we considered the evidence to be of very low certainty and affected by imprecision.

Help-Seeking

Mulfinger et al⁵⁰ reported on participants’ help-seeking behaviour. The outcome was assessed by the General Help-Seeking Questionnaire.⁵⁹ In the RCT, an average of scores from items related to family and friends and to professionals were reported. Higher scores indicate an increased likelihood for seeking help.⁵⁰ A mean score was calculated from the scores of the subscales (range = 1 to 4), with higher scores indicating more empowerment.

The results of the trial showed that at post-intervention (n = 84), participants in the HOP group reported increased help-seeking behaviour compared with those in the TAU group (mean between-group difference for change from baseline = 0.77; 95% CI, 0.36 to 1.17). However, at 6-week follow-up (n = 62), there was no significant difference between the groups, but this evidence was affected by imprecision. As for seeking help from professionals, participants in HOP group reported significantly higher improvement compared with those in the TAU group at post-intervention (mean between-group difference for change from baseline = 0.60; 95% CI, 0.15 to 1.05; n = 84) and at 6-week follow-up (mean between-group difference for change from baseline = 0.82; 95% CI, 0.32 to 1.32, n = 62). Overall, we conclude that peer support may be favoured compared with no peer support in improving help-seeking behaviour among youth, but the evidence supporting this conclusion is very uncertain.

Hopelessness

Mulfinger and colleagues⁵⁰ reported on participants’ feeling of hopelessness. The outcome was assessed by the Beck’s Hopelessness Scale (brief version),⁶⁰ a 4-item questionnaire (range = 4 to 24) with higher scores indicating increased hopelessness.

The trial showed that at post-intervention and at 6-week follow-up, there were no significant differences between the HOP and TAU groups in change from baseline of mean scores. The mean between-group differences for change from baseline were 0.51 (95% CI, –1.88 to 0.85) and 1.22 (95% CI, –2.68 to 0.24) at post -intervention (n = 84) and at 6-week follow-up (n = 62), respectively. Thus, there may be little to no difference in the effect of peer support on feeling of hopelessness compared with TAU; however, we considered the evidence to be of very low certainty and affected by imprecision.

Stage of Recovery

Mulfinger and colleagues⁵⁰ reported on participants’ self-reported stage of recovery. The outcome was assessed by Self-Identified Stage of Recovery Scale,⁶¹ in which the total score ranges from 4 to 24, higher scores indicating a better recovery process.

At post-intervention, the trial indicated that there may be little to no difference in the effect of peer support on the stage of recovery compared to TAU, but these findings were very uncertain and affected by imprecision because of the small sample size (n = 84). At the 6-week follow-up (n = 62), the results suggested that peer support may be favoured compared with TAU on the stage of recovery (mean between-group difference for change from baseline = 1.59; 95% CI, 0.10 to 3.07). We assessed the evidence to be of very low certainty and affected by imprecision.

Anxiety

The HOP-C trial^39,40 reported on participants’ self-reported anxiety symptoms. Anxiety symptoms were assessed using Generalized Anxiety Disorder 7-Item scale^62,63 (score range = 0 to 21), with higher scores indicating increased severity of symptoms.⁶³

At post-booster (n = 97)³⁹ and at the 2-month follow-up (n = 55),⁴⁰ there was little to no difference in self-reported improvement in anxiety symptoms between the HOP-C and waitlist groups, but we considered the evidence to be of very uncertain. . . In the HOP group, the mean scores were 1.66 (SD = 0.77), 1.66 (SD = 0.75), and 1.57 (SD = 0.88) at baseline, post-booster, and at 2-month follow-up, respectively. In the waitlist control group, the mean scores at those time points were 1.92 (SD = 0.75), 1.69 (SD = 0.90), and 1.77 (SD = 0.85), respectively.

Depression

Both included RCTs^39,40,50 reported on depression symptoms. Self-reported symptoms of depression were measured at post-intervention, post-booster, and at follow-up (6 weeks⁵⁰ to 2 months⁴⁰ after core sessions), using the 10-item Center for Epidemiologic Studies Depression (CES-D-10) scale³⁹ or the Center for Epidemiologic Studies Depression (CES-D) scale⁵⁰ scales. CES-D⁶⁴ is a 20-item scale to assess symptoms of depression and to identify at-risk individuals for depression; total scores range from 0 to 60.⁶⁵ CES-D-10^66,67 is a shorter 10-item version of the CES-D, in which the scores range from 0 to 30. In both measures, higher scores indicate increasing severity of symptoms.

At post-intervention (n = 84), in 1 RCT there was little to no difference in symptom improvement between HOP and TAU groups (mean between-group difference for change from baseline = 1.25; 95% CI, –4.87 to 2.38).⁵⁰ At post-booster (n = 97), results from the Conley et al. study³⁹ showed little to no difference between the HOP-C and waitlist groups in improving symptoms of depression; we found that the findings for both these time points were very uncertain and affected by imprecision. At the longest follow-up (6 weeks⁵⁰ to 2 months⁴⁰ after core sessions; n = 117), the results were heterogenous. Findings from the study by Mulfinger et al.⁵⁰ favoured HOP at 6 weeks after the sessions (mean between-group difference for change from baseline = 7.25; 95% CI, –10.85 to –3.65), whereas Conley et al.⁴⁰ found little to no difference between the groups at 2 months after the sessions. In the HOP group, the mean scores were 1.74 (SD = 0.58), and 1.54 (SD = 0.70) at baseline and at 2-month follow-up, respectively. In the waitlist control group, the scores at those time points were 1.65 (SD = 0.59) and 1.39 (SD = 0.77), respectively (P = 0.860); we consider the evidence to be of very uncertain.

Health Care Resource Utilization

We did not locate any studies that evaluated or reported on health care resource utilization.

Social Outcomes

We did not locate any studies that evaluated or reported on social outcomes.

Question 2: Safety

We identified no relevant studies that provided outcome data regarding the safety of peer support programs compared with interventions without peer support in the management of mental health concerns among youth.

Environmental Scan of Program Evaluation Methods

Methods

Study Design

An ES was conducted to identify and describe program evaluation methods and guidelines in Canada and internationally, program evaluation characteristics and components, and any findings of completed program evaluations in Canada. The findings presented in this ES are based on a limited literature search and information obtained through targeted stakeholder consultations and stakeholder feedback. We used the limited literature search and targeted stakeholder consultations to inform the decision problem related to understanding how youth peer support programs are evaluated to support the design and implementation of these programs.

Literature Search Methods

The search for literature describing program evaluation aspects was performed by an information specialist using a peer-reviewed search strategy according to the PRESS Peer Review of Electronic Search Strategies checklist.³¹ The search strategy is available on request.

Published literature was identified by searching the following bibliographic databases: MEDLINE All (1946‒) via Ovid, Embase (1974‒) via Ovid, PsycInfo via Ovid, Cochrane Central Register of Controlled Trials via Ovid, Scopus, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) via EBSCO. All Ovid searches, with the exception of Cochrane Central Register of Controlled Trials, were run simultaneously as a multi-file search. Duplicates were removed using Ovid deduplication for multi-file searches, followed by manual deduplication in Endnote. The search strategy comprised both controlled vocabulary, such as the National Library of Medicine’s MeSH (Medical Subject Headings), and keywords. The main search concepts were peer support programs and youth with mental health concerns.

The search was limited to English- and French-language documents published between January 1, 2006, and January 17, 2022. Conference abstracts were excluded from the search results. Regular alerts updated the search until the publication of the final report.

Grey literature (literature that is not commercially published) was identified by searching sources listed in relevant sections of the Grey Matters: A Practical Tool For Searching Health-Related Grey Literature checklist,³² which includes the websites of regulatory agencies, HTA agencies, clinical guideline repositories, SR repositories, patient-related groups, and professional associations. Google was used to search for additional internet-based materials. These searches were supplemented by reviewing bibliographies of key papers and through contacts with experts and industry, as appropriate. Refer to Appendix 1 for more information on the grey literature search strategy.

Screening and Selecting Publications for Inclusion

One author independently screened and retrieved citations using management software DistillerSR (Evidence Partners, Ottawa, Canada). In the first level of screening, the author reviewed the titles and abstracts and retrieved and assessed potentially relevant articles for inclusion. The final selection of full-text articles was based on the inclusion criteria presented in Table 6. Articles that were published in a language other than English or French were excluded. All publication types were eligible. We excluded any articles that did not adhere to the definition of formal peer support programs and did not identify or describe information relevant to program evaluation methodology or outcomes.

Table 6

Components for Literature Screening and Information Gathering.

Consultation Methods

We conducted targeted consultations with key informants involved in program evaluation for peer support programs for youth mental health to fill gaps in knowledge and to provide organizational perspectives. We adopted a purposive sampling approach to identify representatives from various organizations across Canada that offered peer support for youth mental health that included some component of program evaluation. We identified stakeholders through CADTH’s network of liaison officers situated across Canada, referred through other informants during consultations, and through internet searching. One researcher reached out to stakeholders via email and interviewed those willing or able to participate. The researcher conducted the consultations with each key informant via Zoom using a semi-structured interview format. We developed the interview questions based on the research questions, and included questions related to how program evaluation was conducted within the organization that the informant represented, methods and resources used to inform program evaluation, and outcomes that are captured through evaluation. In addition to understanding the methods of program evaluation, equity considerations related to program evaluation were sought during consultations. When possible, representatives shared additional documents and resources to provide examples of what program evaluation efforts look like within their organization and what informs their program evaluation processes.

Six of the consultations followed the same original semi-structured interview guide. Upon analysis of the initial interviews and new emerging insights, the researcher refined the semi-structured interview guide to explore newly identified and targeted information for the remaining consultation (refer to Appendix 4 for the interview guide). Before each consultation, we obtained key informants’ consent to participate and informed them how we will use the information in the final report. Consultations were recorded, and transcripts of the consultations were generated using Microsoft Word and reviewed by the researcher. Key informants involved in the consultations and other relevant stakeholders were also asked to provide feedback on the draft report after completion.

Synthesis Approach

One researcher conducted a descriptive analysis of the literature and consultation transcripts. To do so, the researcher first identified and summarized completed evaluations and methods guidelines identified in the literature, including article characteristics such as author, year of publication, and country in which the evaluation was completed using Microsoft Word. Relevant characteristics are presented in tabular form in Appendix 6 and narratively summarized in the Findings section.

To identify the characteristics and methodology that guide program evaluation, the researcher then examined the identified literature and consultation transcripts to systematically identify and sort information relevant to program evaluation characteristics, methods, outcomes, and equity considerations into relevant categories. The researcher exported the categories to a table in a Microsoft Word document and shared the table with a second and third researcher for discussion. The 3 researchers compared and adjusted the categories in regular meetings. The lead researcher then narratively summarized the categories, formulating a description of program evaluation methods and characteristics in the findings. Information related to program evaluation characteristics, methods, guiding principles and resources, and outcomes measured are presented in Appendix 8.

Discussion

Because peer support is based on a recovery-oriented model of mental health,^3,13 we prioritized recovery-oriented outcomes. Recovery is an ongoing process to regain a meaningful life even with persisting symptoms, is unique for each individual, and depends on one’s family and community connections, social and economic circumstances, and their individual identity. Outcomes that measure recovery focus on a holistic improvement in an individual’s quality of life through increased social connections and emphasize resilience and control over one’s own life.⁸⁵ Recovery was consistently brought up as the most important outcome or goal of peer support by program representatives and peer support youth advisors. The peer support youth advisors we spoke with all agreed that recovery-oriented outcomes (i.e., peer journey and relationship to recovery, such as community integration, overall fulfillment, emotional regulation, empowerment, education, employment, and social connections) were central to their experiences with peer support. Additionally, the peer support youth advisors explained that recovery is not a finite outcome; rather, it is a subjective or personal journey whereby they continuously make positive movements in their own life. One advisor shared that youth are accepting that they may reach a point where they are not getting better or worse but are maintaining their mental health through peer support. Moreover, because recovery is a process, it points to the benefits of outcomes being measured over time (i.e., not at a single point).

Our SR did not find any information related to the safety of peer support programs for youth peer support users. However, issues related to safety were raised by our peer support youth advisors who had experiences as workers. They spoke of the importance of setting professional boundaries between peer support service users and workers, such as finding a balance between being easily accessible to service users via their professional phone and being able to turn it off. They also spoke about the need for a space where they can connect and have an opportunity to reaffirm that they know what they are doing. “The infrastructure of peer support is often an afterthought about how it will help someone coming into this role — What are their needs going to be? How will this peer have a community of like peers so they’re not isolated? How are we building community? Supervision? A processing space? A place for them to ask questions? A place to say, ‘I’m not doing well’?” This points to the need for sustained recognition that youth peer support workers are themselves in recovery and may need support themselves. There are potential risks to youth peer support users and workers if appropriate training and supports are not carefully considered, developed, and integrated in advance into the peer support program, including the delivery of safe care. These risks can potentially lead to staff burnout and inadvertently affect the youth who use the service. As a whole, it highlights the benefits of formal, structured peer support programs that involve trained peer support workers and an organization that supports them.

In our review, we found the overall treatment effect of peer support to be uncertain, but our peer support youth advisors described the benefits of peer support programs in terms of providing accessible mental health support. They expressed that peer support can be a first point of contact for a lot of youth, and it can be easier to approach peers and ask where to be referred. Moreover, peer support services are perceived as convenient and accessible, and offer a low-barrier, low-commitment service. Importantly, peer support provides an environment where youth peer support advisors described feeling safe and comfortable.

The peer support advisors shared that it was easier opening up to and speaking with peers about their mental health because of their shared lived experience. For the peer support youth advisors we spoke with, this meant that they felt the peer support workers had similar experiences to them, which made it easier for them to relate and understand where they were coming from. This ability to relate and normalize lived experiences with mental health challenges reduced stigma. They noted that it was not as easy to open up to clinical therapists. One said that some youth have had bad experiences in the psychiatry sector, so peer support may feel safer for them. Similarly, many program representatives noted that youth are more likely to engage with mental health care through informal practices such as peer support rather than those offered in a clinical setting such as formal psychology. One advisor described how they did not feel comfortable discussing suicidal ideation openly in a clinical setting for fear that it might be alarming to their care provider but felt comfortable doing so with a peer who was candid about their own experiences and who normalized them. Youth peer support advisors we spoke with consistently articulated how much they valued peer support and how it played an important role in their recovery.

Although our review did not evaluate different modalities of delivering peer support, 1 youth peer support advisor explained youth in rural communities seeking in-person support may know people working in centres. As a result, they may not feel comfortable sharing sensitive information about themselves for fear of it getting back to their parents or others in their small community. This may lead them to not use in-person services, and they may prefer to access virtual services that are removed from their community. Some of the peer support advisors spoke about the convenience of virtual services and how it facilitates the sharing of resources electronically. Similarly, it allows some programs to broaden their reach and provide access to youth who live in rural or remote areas. However, it is not without its limitations because individuals without access to the internet cannot access some peer support services. In-person support can help bridge that gap; the peer support youth advisors spoke about peer support workers meeting youth in person (e.g., drop-in, by appointment, or meeting in the community), and the value in being reachable via a cell phone provided by the peer support program.

There may be a role for peer support in reducing inappropriate mental health care, but it may also result in increased access to appropriate mental health care, which in some contexts may include ED visits and hospitalizations. Increased health care resource use may be an indicator that peer support is working (i.e., youth are seeking treatment of underlying metal health conditions due to reduced stigma and increased self-efficacy). Indeed, our stakeholder engagements and consultations with peer support youth advisors similarly highlighted the significance of contextualizing resource utilization outcomes in light of the overarching recovery-oriented aims of peer support. Studies looking at peer support for adult mental health often include reduced ED use or hospitalizations as evidence of the effectiveness of peer support.²⁹ This is premised on individuals becoming engaged in the process of recovery and improving their ability to cope through peer support, which results in less need to access crisis mental health care (ED visits), or experiencing less severe symptoms leading to fewer inpatient stays (hospitalizations). The ED is typically recognized as an inappropriate setting for mental health care, particularly when used repeatedly.^86,87 However, with the fragmentation of mental health services in many parts of Canada,^88,89 it may be the only accessible point of contact for some youth in crisis. Thus, careful interpretation is required when considering the complicated relationship between peer support programs and health care resource use.

In our scan of methods for and evaluations of peer support programs, several program representatives described how they sought to balance the benefits of formalizing and standardizing peer support programs and their evaluation with the informal and flexible nature of peer support which is central to its integrity as an intervention. Although our respondents were all representatives of formal peer support programs, they expressed worries that increasing pressures to formalize programs and evaluation could impact the fidelity of the peer support being delivered. However, these risks appear to be outweighed by the positive dimensions of standardizing some aspects of peer support (through program design including training of peer support workers).

The program representatives we spoke with shared a principle guiding evaluations of peer support programs was that they were adhering to a recovery-oriented model of care. This meant that most evaluations included some form of recovery-oriented outcomes and reviewed how a program supported a youth’s recovery. Program representatives highlighted that recovery is unique to the individual and occurs in the context of a programs’ specific set of aims or objectives and can be evaluated in different ways so evaluations can vary across programs. Based on this, it is important for evaluations of peer support programs for youth mental health to select appropriate evaluation aims and outcomes based on their program’s specific aims, objectives, and the youth population they serve. Repeating measurements over time (longitudinal measurements) and possibly adjusting the evaluation according to changes in recovery over time could help to understand the effect that programs may have on individual recovery. As a flexible and tailorable intervention, the context matters in assessing its impact, highlighting the need for context-specific evaluations and selecting recovery-oriented outcomes that are consistent with the aims of the program.

Co-design is a process that enables participants to be involved in the design of the program evaluation and is an important principle that can ensure that the data being captured are relevant to the needs of the youth involved and can contribute to the recovery model. Co-designed evaluations can also be used highlight or capture equity considerations within the program and evaluation process and ensure safety and appropriate cultural competency that fits the needs of the youth involved in the program. Involving youth with lived experience of peer support in the co-design of the program evaluation can inform the needs of the program to better align with and reflect the needs and identities of its users. One youth peer support advisor described the role of youth involved in an evaluation as helping staff bridge to youth by ensuring the research is explained in plain language. The same advisor shared that this involvement was especially important when working with an outside evaluator who did not know how the program functions or the language used by a program.

Unsurprisingly, given the importance of local context, we found that organizations and programs vary in the aims and objectives of their evaluations. Some programs use evaluation as an opportunity to better understand how peer support “works” (i.e., leads to short- and long-term improvements in youth’s recovery, contributes to improved access to mental health care, and reduces inappropriate mental health care). But for many programs, evaluation is used to ensure that the program meets the needs of the youth (peer users and peer workers) and as a way of ensuring the integrity or the fidelity of the program. These evaluations often focus on the experience and feedback from those involved in the program for the purpose of quality improvement and are designed for the specific purpose of the program evaluation. At the same time, evaluation is an opportunity to build an evidence base around the use of peer support for youth mental health. Regardless of the specific aim or objective of the evaluation, the youth peer support advisors we spoke with shared that transparency of why the evaluation was being conducted and what was being done with their data were essential for youth buy-in to the evaluation, which highlights the benefits of a co-design approach to evaluation.

In addition to having multiple aims, programs often must balance program needs and the identified needs of youth and sometimes those of the larger organization or funders. Our consultations also highlighted the challenges that may arise when the program needs do not fully align with those of the larger organization or funders. To secure funding, program evaluation may be tailored in a way that highlights the use of program outputs (e.g., number of contacts); however, this may not capture how the programs support the individuals involved (i.e., quality improvement) or for understanding the mechanisms and context in which peer support works. Program representatives spoke about the importance of flexibility and understanding that evaluation should primarily focus on the needs of the individuals engaged in the program. Programs vary in their capacity to design and conduct evaluations of peer support programs for youth, this includes methods support (e.g., data collection, analysis) and funding. Accounting for the resources needed to conduct evaluations in funding agreements is another avenue that can be used to support advancements in evaluating peer support programs.

Equity in peer support programs requires recognizing the existing inequitable distribution of poor mental health among youth who are systematically disadvantaged,⁶ and the need for equitable access to inclusive and desirable peer support programs for these youth.⁹⁰ In our clinical SR, we aimed to identify specific groups of youth who are disadvantaged who experience an inequitable burden of mental health challenges and access to inclusive mental health services using PROGRESS-Plus,²³ the available published and grey literature on peer support, discussions with clinical and content experts, and through existing descriptions of peer support programs explicitly designed to target or serve youth who are disadvantaged. These groups of youth include but are not limited to youth members of the 2SLGBTQ+ community, Indigenous youth, Black youth and youth of colour, youth members of newcomer communities, youth experiencing homelessness or street involvement, youth with disabilities, and youth living in rural and remote communities. The trials included in the SR of clinical effectiveness were predominantly conducted among White, heterosexual, female youth. We did not identify any information on subgroups based on PROGRESS-Plus factors.

The results of our SR could not contribute to our understanding about the role of equity in peer support in terms of effectiveness and safety, our engagement with youth peer support advisors pointed to some ways equity might affect the effectiveness and safety of peer support programs. One peer support advisor described how a lack of shared lived experience or understanding of racism and discrimination is a barrier to peer support: “They don’t understand anything I’m going through. I need to explain this whole backstory about colourism and racism. If they don’t understand that, it sometimes feels like it’s not even worth the effort to go see them.”

During recruitment and training of youth peer support workers, programs have the opportunity to ensure they can meet the needs of youth and provide culturally competent support to positively influence the experience of the peer support user. One example of this was outlined during consultation with Foundry Central Office, where a process for developing and including a justice, equity, diversity, and inclusion (JEDI) lens across the organization was described.

Equity was a concern in most peer support programs and in their evaluation processes; however, the definitions of equity and approaches used to address equity concerns varied. Youth peer support advisors and program representatives shared that equity ensures all youth are able to access the service. Peer support youth advisors expressed wanting to see peer supporters who are chronically ill or disabled, are part of the 2SLGBTQ+ community, have experienced homelessness, and are from other populations who experience marginalization or disadvantage. “There are so many intersections that, often, some are missed.” They desired to see representation in all aspects of peer support programs, including involving youth in the design and evaluation of peer support programs.

Because equity is as an integral concept to peer support programs, it also needs to be integral to the evaluation approach and cannot be an add-on at the point of evaluation. Involving youth with lived experience of peer support in the co-design of the program evaluation can inform the needs of the program and to better align with and reflect the needs and identities of its users. Instead of seeking only the perspectives of professionals, using evaluation co-design includes the voice of the youth involved to identify and address gaps in equity. For programs to address equity concerns and be culturally competent, program leaders and staff should aim to prioritize the appropriate resources and time and continuously build ongoing relationships with communities.

Abbreviations

2SLGBTQ+

2-Spirit, lesbian, gay, bisexual, transgender, queer, and other sexual identities

CES-D

Center for Epidemiologic Studies-Depression

C-PROM

Canadian Personal Recovery Outcome Measure

CYPCO

Children and Young People Community Organizations

ED

emergency department

ES

Environmental Scan

GAD-7

General Anxiety Disorder 7-item

GRADE

Grading of Recommendations Assessment, Development and Evaluation

HOP

Honest, Open, Proud

HOP-C

Honest, Open, Proud–College

HRQoL

health-related quality of life

HTA

Health Technology Assessment

PHQ-9

Patient Health Questionnaire-9

PRISMA

Preferred Reporting Items for Systematic reviews and Meta-Analyses

PSIQI

Peer Support Integrity, Quality and Impact

RCT

randomized controlled trial

RoB 2

Risk of Bias 2

SD

standard deviation

SR

systematic review

SSMIS-SF

Self-Stigma of Mental Illness Scale–Short Form

TAU

treatment as usual

TAY

Transitional Aged Youth

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Appendix 1. Literature Search Strategy

Note that this appendix has not been copy-edited.

Clinical Literature Search

Overview

Interface: Ovid

Databases:

• MEDLINE All (1946-present)
• Embase (1974-present)
• PsycInfo (1806-present)
• Note: Subject headings and search fields have been customized for each database. Duplicates between databases were removed in Ovid.

Date of search: December 17, 2021

Alerts: Biweekly search updates until project completion

Search filters applied: Systematic reviews; meta-analyses; network meta-analyses; health technology assessments; overview of reviews; randomized controlled trials; controlled clinical trials; observational studies.

Limits:

• Publication date limit: 2006-present
• Language limit: English and French language
• Conference abstracts: excluded

Table 7

Syntax Guide.

Multi-Database Strategy

1. Peer group/
2. ((Peer* or mentor*) adj2 (support* or relationship* or help* or intervention* or network* or discussion* or service* or program* or club* or based or coach* or counsel* or exchange* or guide* or group* or influence* or led or deliver* or education or involve* or advocate* or communication* or center* or centre* or lead* or model* or worker* or specialist* or run or partner* or provided or role* or interaction* or driven or advice or assistance or facilitat* or consult*)).ti,kf,dq.
3. ((Peer* or mentor*) adj1 (support* or relationship* or help* or intervention* or network* or discussion* or service* or program* or club* or based or coach* or counsel* or exchange* or guide* or group* or influence* or led or deliver* or education or involve* or advocate* or communication* or center* or centre* or lead* or model* or worker* or specialist* or run or partner* or provided or role* or interaction* or driven or advice or assistance or facilitat* or consult*)).ab. /freq=2
4. Peer* support*.ab,dq.
5. (peer* to peer* or peer mentor*).ti,ab,kf,dq.
6. ((individual* or peer* or mentor*) adj4 lived experience*).ti,ab,kf,dq.
7. or/1-6
8. mental health care/ or mental health service/ or mental health/ or mental disease/ or adjustment disorder/ or alexithymia/ or exp anxiety disorder/ or complicated grief/ or exp dissociative disorder/ or exp emotional disorder/ or exp experimental mental disease/ or hikikomori/ or exp mental deficiency/ or mental infantilism/ or mental instability/ or mental overstimulation/ or exp mood disorder/ or exp neurosis/ or organic brain syndrome/ or organic psychosyndrome/ or exp personality disorder/ or psychiatric complication/ or exp psychosexual disorder/ or exp psychosis/ or exp psychosomatic disorder/ or exp psychotrauma/ or exp schizophrenia spectrum disorder/ or stupor/ or exp suicidal behavior/ or exp eating disorder/
9. (mental disorder* or mental health or mental disease* or mental illness* or posttraumatic or PTSD or PTD or trauma* or psychiatric illness* or psychiatric disease* or psychiatric disorder* or psychotic disorder* or psychiatric diagnos?s or behavio?r disorder* or mood disorder* or affective disorder* or psychological disorder* or psychological disease* or psychological illness* or psychological diagnos?s).ti,ab,kf,dq.
10. (anxiety or depress* or panic disorder* or neuroses or neurosis or neurotic or bipolar or schizophreni* or personality disorder* or psychosis or anorexia or eating disorder* or bulimia).ti,ab,kf,dq.
11. (suicid* or parasuicid*).ti,ab,kf,dq.
12. (self adj2 (injur* or mutilat* or inflict* or wound* or harm* or cut* or hurt* or destruct* or wound*)).ti,ab,kf,dq.
13. or/8-12
14. Young adult/
15. Juvenile/
16. Adolescent/
17. (child* or paediatric* or pediatric* or girl* or boy* or kid* or teen* or tween* or youngster* or youth* or preteen* or adolescen* or school age* or preadolescen* or juvenile* or young adult* or young people* or young person* or student* or early adult* or emerging adult* or college* or universit* or high school* or post secondary or postsecondary or classmate* or class mate*).ti,ab,kf,dq.
18. young.ti,kf.
19. or/14-18
20. 7 and 13 and 19
21. (Peer* and mental*).ti.
22. 20 or 21
23. 22 not (conference abstract or conference review).pt.
24. 23 use oemezd
25. exp Peer group/
26. ((Peer* or mentor*) adj2 (support* or relationship* or help* or intervention* or network* or discussion* or service* or program* or club* or based or coach* or counsel* or exchange* or guide* or group* or influence* or led or deliver* or education or involve* or advocate* or communication* or center* or centre* or lead* or model* or worker* or specialist* or run or partner* or provided or role* or interaction* or driven or advice or assistance or facilitat* or consult*)).ti,kf.
27. ((Peer* or mentor*) adj1 (support* or relationship* or help* or intervention* or network* or discussion* or service* or program* or club* or based or coach* or counsel* or exchange* or guide* or group* or influence* or led or deliver* or education or involve* or advocate* or communication* or center* or centre* or lead* or model* or worker* or specialist* or run or partner* or provided or role* or interaction* or driven or advice or assistance or facilitat* or consult*)).ab. /freq=2
28. Peer* support*.ab.
29. (peer* to peer* or peer mentor*).ti,ab,kf.
30. ((individual* or peer* or mentor*) adj4 lived experience*).ti,ab,kf.
31. or/25-30
32. Mental health/ or exp Mental health services/ or exp Community Mental Health Centers/ or Mental health recovery/ or Mentally Ill Persons/
33. mental disorders/ or exp anxiety disorders/ or exp "bipolar and related disorders"/ or exp "disruptive, impulse control, and conduct disorders"/ or exp dissociative disorders/ or exp elimination disorders/ or exp "feeding and eating disorders"/ or exp mood disorders/ or motor disorders/ or neurotic disorders/ or exp paraphilic disorders/ or exp personality disorders/ or exp "schizophrenia spectrum and other psychotic disorders"/ or exp sexual dysfunctions, psychological/ or exp sleep wake disorders/ or exp somatoform disorders/ or exp "trauma and stressor related disorders"/ or depression/ or Schizophrenia, Childhood/ or Anxiety, Separation/ or exp Self-Injurious Behavior/
34. (mental disorder* or mental health or mental disease* or mental illness* or posttraumatic or PTSD or PTD or trauma* or psychiatric illness* or psychiatric disease* or psychiatric disorder* or psychotic disorder* or psychiatric diagnos?s or behavio?r disorder* or mood disorder* or affective disorder* or psychological disorder* or psychological disease* or psychological illness* or psychological diagnos?s).ti,ab,kf.
35. (anxiety or depress* or panic disorder* or neuroses or neurosis or neurotic or bipolar or schizophreni* or personality disorder* or psychosis or anorexia or eating disorder* or bulimia).ti,ab,kf.
36. (suicid* or parasuicid*).ti,ab,kf.
37. (self adj2 (injur* or mutilat* or inflict* or wound* or harm* or cut* or hurt* or destruct* or wound*)).ti,ab,kf.
38. or/32-37
39. Adolescent/ or Young adult/ or Pediatrics/
40. (child* or paediatric* or pediatric* or girl* or boy* or kid* or teen* or tween* or youngster* or youth* or preteen* or adolescen* or school age* or preadolescen* or juvenile* or young adult* or young people* or young person* or student* or early adult* or emerging adult* or college* or universit* or high school* or post secondary or postsecondary or classmate* or class mate*).ti,ab,kf.
41. young.ti,kf.
42. or/39-41
43. 31 and 38 and 42
44. (Peer* and mental*).ti.
45. 43 or 44
46. 45 use medall
47. Peers/
48. Peer counseling/
49. Peer relations/
50. ((Peer* or mentor*) adj2 (support* or relationship* or help* or intervention* or network* or discussion* or service* or program* or club* or based or coach* or counsel* or exchange* or guide* or group* or influence* or led or deliver* or education or involve* or advocate* or communication* or center* or centre* or lead* or model* or worker* or specialist* or run or partner* or provided or role* or interaction* or driven or advice or assistance or facilitat* or consult*)).ti,id.
51. ((Peer* or mentor*) adj1 (support* or relationship* or help* or intervention* or network* or discussion* or service* or program* or club* or based or coach* or counsel* or exchange* or guide* or group* or influence* or led or deliver* or education or involve* or advocate* or communication* or center* or centre* or lead* or model* or worker* or specialist* or run or partner* or provided or role* or interaction* or driven or advice or assistance or facilitat* or consult*)).ab. /freq=2
52. Peer* support*.ab.
53. (peer* to peer* or peer mentor*).ti,ab,id.
54. ((individual* or peer* or mentor*) adj4 lived experience*).ti,ab,id.
55. or/47-54
56. exp Mental health/
57. exp Mental health services/
58. mental disorders/ or exp affective disorders/ or exp anxiety disorders/ or exp bipolar disorder/ or borderline states/ or exp chronic mental illness/ or exp dissociative disorders/ or exp eating disorders/ or gender dysphoria/ or mental disorders due to general medical conditions/ or exp neurosis/ or exp paraphilias/ or exp personality disorders/ or exp psychosis/ or serious mental illness/ or exp sleep wake disorders/ or exp somatoform disorders/ or exp "stress and trauma related disorders"/ or exp thought disturbances/
59. exp suicide/
60. Suicidal ideation/
61. exp Self-Injurious Behavior/
62. (mental disorder* or mental health or mental disease* or mental illness* or posttraumatic or PTSD or PTD or trauma* or psychiatric illness* or psychiatric disease* or psychiatric disorder* or psychotic disorder* or psychiatric diagnos?s or behavio?r disorder* or mood disorder* or affective disorder* or psychological disorder* or psychological disease* or psychological illness* or psychological diagnos?s).ti,ab,id.
63. (anxiety or depress* or panic disorder* or neuroses or neurosis or neurotic or bipolar or schizophreni* or personality disorder* or psychosis or anorexia or eating disorder* or bulimia).ti,ab,id.
64. (suicid* or parasuicid*).ti,ab,id.
65. (self adj2 (injur* or mutilat* or inflict* or wound* or harm* or cut* or hurt* or destruct* or wound*)).ti,ab,id.
66. or/56-65
67. ("200" or "320").ag.
68. Adolescent Attitudes/ or Adolescent Behavior/ or Adolescent Health/ or Adolescent Development/ or Adolescent Psychology/ or Early Adolescence/ or Adolescent Psychiatry/ or Adolescent Psychotherapy/ or Adolescent psychopathology/ or Emerging adulthood/ or Childhood development/
69. (child* or paediatric* or pediatric* or girl* or boy* or kid* or teen* or tween* or youngster* or youth* or preteen* or adolescen* or school age* or preadolescen* or juvenile* or young adult* or young people* or young person* or student* or early adult* or emerging adult* or college* or universit* or high school* or post secondary or postsecondary or classmate* or class mate*).ti,ab,id.
70. young.ti,id.
71. or/67-70
72. 55 and 66 and 71
73. (Peer* and mental*).ti.
74. 72 or 73
75. 74 use psyh
76. 24 or 46 or 75
77. (systematic review or meta-analysis).pt.
78. meta-analysis/ or systematic review/ or systematic reviews as topic/ or meta-analysis as topic/ or "meta analysis (topic)"/ or "systematic review (topic)"/ or exp technology assessment, biomedical/ or network meta-analysis/
79. ((systematic* adj3 (review* or overview*)) or (methodologic* adj3 (review* or overview*))).ti,ab,kf.
80. ((quantitative adj3 (review* or overview* or synthes*)) or (research adj3 (integrati* or overview*))).ti,ab,kf.
81. ((integrative adj3 (review* or overview*)) or (collaborative adj3 (review* or overview*)) or (pool* adj3 analy*)).ti,ab,kf.
82. (data synthes* or data extraction* or data abstraction*).ti,ab,kf.
83. (handsearch* or hand search*).ti,ab,kf.
84. (mantel haenszel or peto or der simonian or dersimonian or fixed effect* or latin square*).ti,ab,kf.
85. (met analy* or metanaly* or technology assessment* or HTA or HTAs or technology overview* or technology appraisal*).ti,ab,kf.
86. (meta regression* or metaregression*).ti,ab,kf.
87. (meta-analy* or metaanaly* or systematic review* or biomedical technology assessment* or bio-medical technology assessment*).mp,hw.
88. (medline or cochrane or pubmed or medlars or embase or cinahl).ti,ab,hw.
89. (cochrane or (health adj2 technology assessment) or evidence report).jw.
90. (comparative adj3 (efficacy or effectiveness)).ti,ab,kf.
91. (outcomes research or relative effectiveness).ti,ab,kf.
92. ((indirect or indirect treatment or mixed-treatment or bayesian) adj3 comparison*).ti,ab,kf.
93. (meta-analysis or systematic review).md.
94. (multi* adj3 treatment adj3 comparison*).ti,ab,kf.
95. (mixed adj3 treatment adj3 (meta-analy* or metaanaly*)).ti,ab,kf.
96. umbrella review*.ti,ab,kf.
97. (multi* adj2 paramet* adj2 evidence adj2 synthesis).ti,ab,kf.
98. (multiparamet* adj2 evidence adj2 synthesis).ti,ab,kf.
99. (multi-paramet* adj2 evidence adj2 synthesis).ti,ab,kf.
100. or/77-99
101. epidemiologic methods.sh.
102. epidemiologic studies.sh.
103. observational study/
104. observational studies as topic/
105. clinical studies as topic/
106. controlled before-after studies/
107. cross-sectional studies/
108. historically controlled study/
109. interrupted time series analysis/
110. exp seroepidemiologic studies/
111. national longitudinal study of adolescent health/
112. cohort studies/
113. cohort analysis/
114. longitudinal studies/
115. longitudinal study/
116. prospective studies/
117. prospective study/
118. follow-up studies/
119. follow up/
120. followup studies/
121. retrospective studies/
122. retrospective study/
123. case-control studies/
124. exp case control study/
125. cross-sectional study/
126. observational study/
127. quasi experimental methods/
128. quasi experimental study/
129. single-case studies as topic/
130. (observational study or validation studies or clinical study).pt.
131. (observational adj3 (study or studies or design or analysis or analyses)).ti,ab,kf,kw.
132. cohort*.ti,ab,kf,kw.
133. (prospective adj7 (study or studies or design or analysis or analyses)).ti,ab,kf,kw.
134. ((follow up or followup) adj7 (study or studies or design or analysis or analyses)).ti,ab,kf,kw.
135. ((longitudinal or longterm or (long adj term)) adj7 (study or studies or design or analysis or analyses or data)).ti,ab,kf,kw.
136. (retrospective adj7 (study or studies or design or analysis or analyses or data or review)).ti,ab,kf,kw.
137. ((case adj control) or (case adj comparison) or (case adj controlled)).ti,ab,kf,kw.
138. (case-referent adj3 (study or studies or design or analysis or analyses)).ti,ab,kf,kw.
139. (population adj3 (study or studies or analysis or analyses)).ti,ab,kf,kw.
140. (descriptive adj3 (study or studies or design or analysis or analyses)).ti,ab,kf,kw.
141. ((multidimensional or (multi adj dimensional)) adj3 (study or studies or design or analysis or analyses)).ti,ab,kf,kw.
142. (cross adj sectional adj7 (study or studies or design or research or analysis or analyses or survey or findings)).ti,ab,kf,kw.
143. ((natural adj experiment) or (natural adj experiments)).ti,ab,kf,kw.
144. (quasi adj (experiment or experiments or experimental)).ti,ab,kf,kw.
145. ((non experiment or nonexperiment or non experimental or nonexperimental) adj3 (study or studies or design or analysis or analyses)).ti,ab,kf,kw.
146. (prevalence adj3 (study or studies or analysis or analyses)).ti,ab,kf,kw.
147. or/101-146
148. (Randomized Controlled Trial or Controlled Clinical Trial or Pragmatic Clinical Trial or Clinical Study or Adaptive Clinical Trial or Equivalence Trial).pt.
149. (Clinical Trial or Clinical Trial, Phase I or Clinical Trial, Phase II or Clinical Trial, Phase III or Clinical Trial, Phase IV or Clinical Trial Protocol).pt.
150. Multicenter Study.pt.
151. Clinical Studies as Topic/
152. exp Clinical Trial/ or exp Clinical Trials as Topic/ or Clinical Trial Protocol/ or Clinical Trial Protocols as Topic/ or exp "Clinical Trial (topic)"/
153. Multicenter Study/ or Multicenter Studies as Topic/ or "Multicenter Study (topic)"/
154. Randomization/
155. Random Allocation/
156. Double-Blind Method/
157. Double Blind Procedure/
158. Double-Blind Studies/
159. Single-Blind Method/
160. Single Blind Procedure/
161. Single-Blind Studies/
162. Placebos/
163. Placebo/
164. Control Groups/
165. Control Group/
166. Cross-Over Studies/ or Crossover Procedure/
167. (random* or sham or placebo*).ti,ab,hw,kf,kw.
168. ((singl* or doubl*) adj (blind* or dumm* or mask*)).ti,ab,hw,kf,kw.
169. ((tripl* or trebl*) adj (blind* or dumm* or mask*)).ti,ab,hw,kf,kw.
170. (control* adj3 (study or studies or trial* or group*)).ti,ab,hw,kf,kw.
171. (clinical adj3 (study or studies or trial*)).ti,ab,hw,kf,kw.
172. (Nonrandom* or non random* or non-random* or quasi-random* or quasirandom*).ti,ab,hw,kf,kw.
173. (phase adj3 (study or studies or trial*)).ti,ab,hw,kf,kw.
174. ((crossover or cross-over) adj3 (study or studies or trial*)).ti,ab,hw,kf,kw.
175. ((multicent* or multi-cent*) adj3 (study or studies or trial*)).ti,ab,hw,kf,kw.
176. allocated.ti,ab,hw.
177. ((open label or open-label) adj5 (study or studies or trial*)).ti,ab,hw,kf,kw.
178. ((equivalence or superiority or non-inferiority or noninferiority) adj3 (study or studies or trial*)).ti,ab,hw,kf,kw.
179. (pragmatic study or pragmatic studies).ti,ab,hw,kf,kw.
180. ((pragmatic or practical) adj3 trial*).ti,ab,hw,kf,kw.
181. ((quasiexperimental or quasi-experimental) adj3 (study or studies or trial*)).ti,ab,hw,kf,kw.
182. trial.ti,kf,kw.
183. or/148-182
184. exp animals/
185. exp animal experimentation/
186. exp models animal/
187. exp animal experiment/
188. nonhuman/
189. exp vertebrate/
190. animal.po.
191. or/184-190
192. exp humans/
193. exp human experiment/
194. human.po.
195. or/192-194
196. 191 not 195
197. 183 not 196
198. 100 or 147 or 197
199. 76 and 198
200. limit 199 to (english or french)
201. limit 200 to yr="2006 -Current"
202. limit 201 to yr="2006 -2014"
203. remove duplicates from 202
204. limit 201 to yr="2015 -current"
205. remove duplicates from 204
206. 203 or 205

Other Databases

Cochrane Central Register of Controlled Trials

Same MeSH, keywords, and limits used as per MEDLINE search, excluding study types and human restrictions. Syntax adjusted for Wiley platform. The search strategy is available on request.

CINAHL

Same MeSH, keywords, and limits used as per MEDLINE search, excluding study types and human restrictions. Syntax adjusted for EBSCO platform, including the addition of CINAHL headings. The search strategy is available on request.

Scopus

Same MeSH, keywords, and limits used as per MEDLINE search, excluding study types and human restrictions. Syntax adjusted for Scopus platform. The search strategy is available on request.

Appendix 2. Tables and Figures

Note that this appendix has not been copy-edited.

Figure 1

PRISMA Flow Chart of Selected Reports — Clinical Review.

Table 8

Detailed Characteristics of the Included Trials — Clinical Review.

Table 9

Risk of Bias in the Included Randomized Controlled Trials Assessed Using RoB 2 (Effect of Assignment to the Intervention).

Table 10

Summary of Detailed Findings for Stigma.

Table 11

Summary of Detailed Findings for Self-Efficacy About Secrecy and Disclosing Mental Illness.

Table 12

Summary of Detailed Findings for HRQoL.

Table 13

Summary of Detailed Findings for Empowerment.

Table 14

Summary of Detailed Findings for Social Withdrawal.

Table 15

Summary of Detailed Findings for Help-Seeking.

Table 16

Summary of Detailed Findings for Hopelessness.

Table 17

Summary of Detailed Findings for Stage of Recovery.

Table 18

Summary of Detailed Findings for Clinical Outcomes.

Table 19

GRADE Summary of Findings for Self-Stigma — Clinical Review.

Table 20

GRADE Summary of Findings for Stigma Stress.

Table 21

GRADE Summary of Findings for Self-Efficacy Related to Secrecy and Disclosing of Mental Illness.

Table 22

GRADE Summary of Findings for Attitudes to Disclosure.

Table 23

GRADE Summary of Findings for Disclosure-Related Distress.

Table 24

GRADE Summary of Findings for Secrecy.

Table 25

GRADE Summary of Findings for HRQoL.

Table 26

GRADE Summary of Findings for Empowerment.

Table 27

GRADE Summary of Findings for Social Withdrawal.

Table 28

GRADE Summary of Findings for Help-Seeking.

Table 29

GRADE Summary of Findings for Hopelessness.

Table 30

GRADE Summary of Findings for Stage of Recovery.

Table 31

GRADE Summary of Findings for Symptoms of Anxiety.

Table 32

GRADE Summary of Findings for Symptoms of Depression.

Table 33

Detailed Descriptions of Outcome Measurement Tools.

Appendix 3. List of Excluded Publications and Reasons for Exclusion — Review of Clinical Effectiveness and Safety

Note that this appendix has not been copy-edited.

The citations provided in this list are studies that were excluded after full-text review by 2 independent reviewers as part of the Clinical Review (in reverse chronological and alphabetical order).

Irrelevant Population (n = 84)

1. Ali K, Fassnacht DB, Farrer LM, et al. Recruitment, adherence and attrition challenges in internet-based indicated prevention programs for eating disorders: lessons learned from a randomised controlled trial of ProYouth OZ. Journal of Eating Disorders. 2022;10(1). [PMC free article: PMC8725518] [PubMed: 34983675]
2. Ali SH, Mohsin FM, Banks A, Lynn P, Lim S. Peer-Led, Remote Intervention to Improve Mental Health Outcomes Using a Holistic, Spirituality-Based Approach: Results from a Pilot Study. Community mental health journal. 2021;24. [PMC free article: PMC8475393] [PubMed: 34561834]
3. Johnson BA, Riley JB. Psychosocial impacts on college students providing mental health peer support. J Am Coll Health. 2021;69(2)():232-236. [PubMed: 31532336]
4. Toombs E, Mushquash CJ, Lund J, et al. Adaption and implementation of the Housing Outreach Program Collaborative (HOP-C) North for Indigenous youth. Am J Orthopsychiatry. 2021;91(1)():96-108. [PubMed: 33411554]
5. Onyeka O, Richards M, Tyson McCrea K, et al. The role of positive youth development on mental health for youth of color living in high-stress communities: A strengths-based approach. Psychol Serv. 2021;04():04. [PubMed: 34735195]
6. Gregory D, Van Puymbroeck M, Crowe B, Garst B, Amylon M. The Influence of a Peer Support Camp on Mitigating Emotional Distress in Siblings of Children With Cancer. J Pediatr Oncol Nurs. 2021;():10434542211041929. [PubMed: 34546821]
7. Munson MR, Jaccard J, Scott LD, Jr., et al. Outcomes of a Metaintervention to Improve Treatment Engagement Among Young Adults With Serious Mental Illnesses: Application of a Pilot Randomized Explanatory Design. J Adolesc Health. 2021;69(5):790-796. [PMC free article: PMC8545849] [PubMed: 34099390]
8. Sansom-Daly UM, Wakefield CE, Ellis SJ, et al. Online, Group-Based Psychological Support for Adolescent and Young Adult Cancer Survivors: Results from the Recapture Life Randomized Trial. Cancers (Basel). 2021;13(10):18. [PMC free article: PMC8158368] [PubMed: 34070134]
9. Albritton T, Ford KL, Elsbernd K, et al. Implementing a Peer Advocate Mental Health Digital Intervention Program for Ohio Youth: Descriptive Pilot Study. JMIR mental health. 2021;8(4):e24605. [PMC free article: PMC8105753] [PubMed: 33890868]
10. Allen JP, Narr RK, Nagel AG, Costello MA, Guskin K. The Connection Project: Changing the peer environment to improve outcomes for marginalized adolescents. Dev Psychopathol. 2021;33(2):647-657. [PMC free article: PMC9034648] [PubMed: 32124707]
11. Mohamadi S, Paryab S, Mousavi SA, Keramat A, Motaghi Z, Garkaz O. Comparison of the effect of motivational interview and peer group education on knowledge and performance about puberty and mental health in adolescent girls. Journal of Nursing & Midwifery Sciences. 2021;8(3):178-185.
12. Fokuo J, Maroney MM, Corrigan P. Pilot of a consumer based anti-stigma mentorship program for nursing students. J Public Ment Health. 2020;19(1):51-61.
13. Svetlitzky V, Farchi M, Ben Yehuda A, Start AR, Levi O, Adler AB. YaHaLOM training in the military: Assessing knowledge, confidence, and stigma. Psychol Serv. 2020;17(2):151-159. [PubMed: 31120293]
14. Shankar P, Sievers D, Sharma R. Evaluating the Impact of a School-Based Youth-Led Health Education Program for Adolescent Females in Mumbai, India. Ann Glob Health. 2020;86(1):57. [PMC free article: PMC7292104] [PubMed: 32566485]
15. Chinoda S, Mutsinze A, Simms V, et al. Effectiveness of a peer-led adolescent mental health intervention on HIV virological suppression and mental health in Zimbabwe: protocol of a cluster-randomised trial. Glob Ment Health (Camb). 2020;7():e23. [PMC free article: PMC7490770] [PubMed: 32963795]
16. Kidd SA, Vitopoulos N, Frederick T, et al. Trialing the feasibility of a critical time intervention for youth transitioning out of homelessness. Am J Orthopsychiatry. 2020;90(5):535-545. [PubMed: 32309974]
17. Vanderkruik R, Gist D, Dimidjian S. Preventing eating disorders in young women: An RCT and mixed-methods evaluation of the peer-delivered Body Project. J Consult Clin Psychol. 2020;88(12):1105-1118. [PubMed: 33370134]
18. Ranzenhofer LM, Wilhelmy M, Hochschild A, Sanzone K, Walsh BT, Attia E. Peer mentorship as an adjunct intervention for the treatment of eating disorders: A pilot randomized trial. International Journal of Eating Disorders. 2020;53(5):497-509. [PMC free article: PMC7383944] [PubMed: 32159243]
19. Maselko J, Sikander S, Turner EL, et al. Effectiveness of a peer-delivered, psychosocial intervention on maternal depression and child development at 3 years postnatal: a cluster randomised trial in Pakistan. Lancet Psychiatry. 2020;7(9):775-787. [PMC free article: PMC8015797] [PubMed: 32828167]
20. Stice E, Rohde P, Shaw H, Gau JM. Clinician-led, peer-led, and internet-delivered dissonance-based eating disorder prevention programs: Effectiveness of these delivery modalities through 4-year follow-up. J Consult Clin Psychol. 2020;88(5):481-494. [PMC free article: PMC7810349] [PubMed: 32091226]
21. Shorey S, Chee CYI, Ng ED, Lau Y, Dennis C-L, Chan YH. Evaluation of a technology-based peer-support intervention program for preventing postnatal depression (Part 1): Randomized controlled trial. Journal of Medical Internet Research Vol 21(8), 2019, ArtID e12410. 2019;21(8):. [PMC free article: PMC6744221] [PubMed: 31469084]
22. Nozawa H, Ikegami K, Michii S, et al. Peer counseling for mental health in young people-Randomized clinical trial. Mental Health and Prevention Vol 14 2019, ArtID 200164. 2019;14():.
23. Beveridge J, Phillipou A, Jenkins Z, et al. Peer mentoring for eating disorders: Results from the evaluation of a pilot program. Journal of Eating Disorders Vol 7 2019, ArtID 13. 2019;7():. [PMC free article: PMC6545742] [PubMed: 31171969]
24. Kidd SA, Vitopoulos N, Frederick T, et al. Peer support in the homeless youth context: Requirements, design, and outcomes. Child & Adolescent Social Work Journal. 2019;36(6):641-654.
25. Fan Y, Ma N, Ma L, et al. Feasibility of peer support services among people with severe mental illness in China. BMC Psychiatry. 2019;19(1) (no pagination)():. [PMC free article: PMC6854628] [PubMed: 31727108]
26. Kidd SA, Vitopoulos N, Frederick T, Leon S, Karabanow J, McKenzie K. More than four walls and a roof needed: A complex tertiary prevention approach for recently homeless youth. Am J Orthopsychiatry. 2019;89(2)():248-257. [PubMed: 30382726]
27. Crisanti AS, Murray-Krezan C, Reno J, Killough C. Effectiveness of Peer-Delivered Trauma Treatment in a Rural Community: A Randomized Non-inferiority Trial. Community Ment Health J. 2019;55(7):1125-1134. [PMC free article: PMC6744517] [PubMed: 31338716]
28. Rusch N, Staiger T, Waldmann T, et al. Efficacy of a peer-led group program for unemployed people with mental health problems: Pilot randomized controlled trial. Int J Soc Psychiatry. 2019;65(4):333-337. [PubMed: 31056997]
29. Fuhr DC, Weobong B, Lazarus A, et al. Delivering the Thinking Healthy Programme for perinatal depression through peers: an individually randomised controlled trial in India. Lancet Psychiatry. 2019;6(2):115-127. [PubMed: 30686385]
30. Crisanti AS, Reno J, Salvador JG, Killough C, Greene RN. Perceived helpfulness of peer-delivered trauma specific treatment: A randomized controlled trial. Psychol Serv. 2019;16(3):425-432. [PubMed: 30407046]
31. Pfeiffer PN, King C, Ilgen M, et al. Development and pilot study of a suicide prevention intervention delivered by peer support specialists. Psychol Serv. 2019;16(3):360-371. [PMC free article: PMC6494743] [PubMed: 30382743]
32. Breithaupt L, Eickman L, Byrne CE, Fischer S. REbeL peer education: A model of a voluntary, after-school program for eating disorder prevention. Eat Behav. 2019;32():111-116. [PubMed: 27825587]
33. Haft SL, Chen T, LeBlanc C, Tencza F, Hoeft F. Impact of mentoring on socio‐emotional and mental health outcomes of youth with learning disabilities and attention‐deficit hyperactivity disorder. Child Adolesc Ment Health. 2019;24(4):318-328. [PMC free article: PMC6812582] [PubMed: 31649490]
34. Willging CE, Harkness A, Israel T, et al. A mixed-method assessment of a pilot peer advocate intervention for rural gender and sexual minorities. Community Ment Health J. 2018;54(4):395-409. [PMC free article: PMC5856590] [PubMed: 28918540]
35. Castellanos D, Capo M, Valderrama D, Jean-Francois M, Luna A. Relationship of peer specialists to mental health outcomes in South Florida. Int J Ment Health Syst. 2018;12(1) (no pagination)():. [PMC free article: PMC6195727] [PubMed: 30377441]
36. Johnson S, Lamb D, Marston L, et al. Peer-supported self-management for people discharged from a mental health crisis team: a randomised controlled trial. Lancet. 2018;392(10145):409-418. [PMC free article: PMC6083437] [PubMed: 30102174]
37. Chinman M, McCarthy S, Bachrach RL, Mitchell-Miland C, Schutt RK, Ellison M. Investigating the Degree of Reliable Change Among Persons Assigned to Receive Mental Health Peer Specialist Services. Psychiatr Serv. 2018;69(12):1238-1244. [PubMed: 30286707]
38. Kido Y, Kawakami N, Kayama M. Comparison of hospital admission rates for psychiatric patients cared for by multidisciplinary outreach teams with and without peer specialist: a retrospective cohort study of Japanese Outreach Model Project 2011-2014. BMJ Open. 2018;8(8):e019090. [PMC free article: PMC6104750] [PubMed: 30121587]
39. Fan Y, Ma N, Ma L, Xu W, Steven Lamberti J, Caine ED. A community-based peer support service for persons with severe mental illness in China. BMC Psychiatry. 2018;18(1):170. [PMC free article: PMC5987580] [PubMed: 29866096]
40. Druss BG, Singh M, von Esenwein SA, et al. Peer-Led Self-Management of General Medical Conditions for Patients With Serious Mental Illnesses: A Randomized Trial. Psychiatr Serv. 2018;69(5):529-535. [PMC free article: PMC5930018] [PubMed: 29385952]
41. Schiltz HK, McVey AJ, Dolan BK, et al. Changes in Depressive Symptoms Among Adolescents with ASD Completing the PEERS R Social Skills Intervention. J Autism Dev Disord. 2018;48(3):834-843. [PMC free article: PMC10321229] [PubMed: 29164445]
42. Ren P, Qin X, Zhang Y, Zhang R. Is Social Support a Cause or Consequence of Depression? A Longitudinal Study of Adolescents. Front Psychol. 2018;9():1634. [PMC free article: PMC6132191] [PubMed: 30233469]
43. Baumel A, Tinkelman A, Mathur N, Kane JM. Digital Peer-Support Platform (7Cups) as an Adjunct Treatment for Women With Postpartum Depression: Feasibility, Acceptability, and Preliminary Efficacy Study. JMIR Mhealth Uhealth. 2018;6(2):e38. [PMC free article: PMC5829455] [PubMed: 29439944]
44. Shanta Bridges L, Sharma M, Lee JHS, Bennett R, Buxbaum SG, Reese-Smith J. Using the PRECEDE-PROCEED model for an online peer-to-peer suicide prevention and awareness for depression (SPAD) intervention among African American college students: experimental study. Health promot. 2018;8(1):15-24. [PMC free article: PMC5797304] [PubMed: 29423358]
45. Breithaupt L, Eickman L, Byrne CE, Fischer S. Enhancing empowerment in eating disorder prevention: Another examination of the REbeL peer education model. Eat Behav. 2017;25():38-41. [PubMed: 27329775]
46. Mahlke CI, Priebe S, Heumann K, Daubmann A, Wegscheider K, Bock T. Effectiveness of one-to-one peer support for patients with severe mental illness - a randomised controlled trial. Eur Psychiatry. 2017;42():103-110. [PubMed: 28364685]
47. Kelly E, Duan L, Cohen H, Kiger H, Pancake L, Brekke J. Integrating behavioral healthcare for individuals with serious mental illness: A randomized controlled trial of a peer health navigator intervention. Schizophr Res. 2017;182():135-141. [PubMed: 27793514]
48. Chu BC, Carpenter AL, Wyszynski CM, Conklin PH, Comer JS. Scalable Options for Extended Skill Building Following Didactic Training in Cognitive-Behavioral Therapy for Anxious Youth: A Pilot Randomized Trial. J Clin Child Adolesc Psychol. 2017;46(3):401-410. [PubMed: 25984590]
49. Crooks C, Exner-Cortens D, Burm S, Lapointe A, Chiodo D, Crooks CV. Two Years of Relationship-Focused Mentoring for First Nations, Métis, and Inuit Adolescents: Promoting Positive Mental Health. J Prim Prev. 2017;38(1/2):87-104. [PubMed: 27848172]
50. Ekore R, Ajuwon A, Abdulmalik J, Omigbodun O, Bella-Awusah T. Developing mental health peer counselling services for undergraduate students of a Nigerian university: A pilot study. IFE Psychologia: An International Journal. 2016;24(2):246-258.
51. Mason MJ, Zaharakis NM, Sabo R. Reducing social stress in urban adolescents with peer network counseling. J Child Fam Stud. 2016;25(12):3488-3496.
52. Moir F, Henning M, Hassed C, Moyes SA, Elley CR. A Peer-Support and Mindfulness Program to Improve the Mental Health of Medical Students. Teach Learn Med. 2016;28(3):293-302. [PubMed: 27092397]
53. Thiha P, Pisani AR, Gurditta K, et al. Efficacy of Web-Based Collection of Strength-Based Testimonials for Text Message Extension of Youth Suicide Prevention Program: Randomized Controlled Experiment. JMIR Public Health Surveill. 2016;2(2):e164. [PMC free article: PMC5121531] [PubMed: 27829575]
54. Ciao AC, Latner JD, Brown KE, Ebneter DS, Becker CB. Effectiveness of a peer-delivered dissonance-based program in reducing eating disorder risk factors in high school girls. International Journal of Eating Disorders. 2015;48(6):779-84. [PubMed: 25959408]
55. Letourneau N, Secco L, Colpitts J, Aldous S, Stewart M, Dennis CL. Quasi-experimental evaluation of a telephone-based peer support intervention for maternal depression. J Adv Nurs. 2015;71(7):1587-99. [PubMed: 25705786]
56. Petrova M, Wyman PA, Schmeelk-Cone K, Pisani AR. Positive-Themed Suicide Prevention Messages Delivered by Adolescent Peer Leaders: Proximal Impact on Classmates' Coping Attitudes and Perceptions of Adult Support. Suicide Life Threat Behav. 2015;45(6):651-63. [PMC free article: PMC4540682] [PubMed: 25692382]
57. Simpson A, Flood C, Rowe J, et al. Results of a pilot randomised controlled trial to measure the clinical and cost effectiveness of peer support in increasing hope and quality of life in mental health patients discharged from hospital in the UK. BMC Psychiatry. 2014;14():30. [PMC free article: PMC3922504] [PubMed: 24495599]
58. Russinova Z, Rogers ES, Gagne C, Bloch P, Drake KM, Mueser KT. A randomized controlled trial of a peer-run antistigma photovoice intervention. Psychiatr Serv. 2014;65(2):242-6. [PubMed: 24337339]
59. Noel LT, Rost K, Gromer J. Depression prevention among rural preadolescent girls: A randomized controlled trial. School Social Work Journal. 2013;38(1):1-18.
60. Lee R, Lee KS, Oh E-G, Kim SH. A randomized trial of dyadic peer support intervention for newly diagnosed breast cancer patients in Korea. Cancer Nurs. 2013;36(3):E15-E22. [PubMed: 22964869]
61. Chien WT, Thompson DR. An RCT with three-year follow-up of peer support groups for Chinese families of persons with schizophrenia. Psychiatr Serv. 2013;64(10):997-1005. [PubMed: 23820670]
62. Jennings SJ, Jennings JL. Peer-Directed, Brief Mindfulness Training with Adolescents: A Pilot Study. International Journal of Behavioral Consultation & Therapy. 2013;8(2):23-25.
63. Van Tam V, Larsson M, Pharris A, et al. Peer support and improved quality of life among persons living with HIV on antiretroviral treatment: a randomised controlled trial from north-eastern Vietnam. Health Qual Life Outcomes. 2012;10():53. [PMC free article: PMC3491019] [PubMed: 22606977]
64. Becker CB, McDaniel L, Bull S, Powell M, McIntyre K. Can we reduce eating disorder risk factors in female college athletes? A randomized exploratory investigation of two peer-led interventions. Body Image. 2012;9(1):31-42. [PMC free article: PMC3246101] [PubMed: 22019502]
65. Proudfoot J, Parker G, Manicavasagar V, et al. Effects of adjunctive peer support on perceptions of illness control and understanding in an online psychoeducation program for bipolar disorder: a randomised controlled trial. J Affect Disord. 2012;142(1-3):98-105. [PubMed: 22858215]
66. van Gestel-Timmermans H, Brouwers EP, van Assen MA, van Nieuwenhuizen C. Effects of a peer-run course on recovery from serious mental illness: a randomized controlled trial. Psychiatr Serv. 2012;63(1):54-60. [PubMed: 22227760]
67. Renner W, Banninger-Huber E, Peltzer K. Culture-Sensitive and Resource Oriented Peer (CROP)-Groups as a community based intervention for trauma survivors: A randomized controlled pilot study with refugees and asylum seekers from Chechnya. Australasian Journal of Disaster and Trauma Studies. 2011;2011(1):1-13.
68. Struchen MA, Davis LC, Bogaards JA, et al. Making connections after brain injury: Development and evaluation of a social peer-mentoring program for persons with traumatic brain injury. J Head Trauma Rehabil. 2011;26(1):4-19. [PubMed: 21209559]
69. Balaji M, Andrews T, Andrew G, Patel V. The acceptability, feasibility, and effectiveness of a population-based intervention to promote youth health: an exploratory study in Goa, India. J Adolesc Health. 2011;48(5):453-60. [PMC free article: PMC4991743] [PubMed: 21501803]
70. Landers GM, Zhou M. An analysis of relationships among peer support, psychiatric hospitalization, and crisis stabilization. Community Ment Health J. 2011;47(1):106-12. [PubMed: 19551502]
71. Sledge WH, Lawless M, Sells D, Wieland M, O'Connell MJ, Davidson L. Effectiveness of peer support in reducing readmissions of persons with multiple psychiatric hospitalizations. Psychiatr Serv. 2011;62(5):541-4. [PubMed: 21532082]
72. Letourneau N, Stewart M, Dennis CL, Hegadoren K, Duffett-Leger L, Watson B. Effect of home-based peer support on maternal-infant interactions among women with postpartum depression: a randomized, controlled trial. Int J Ment Health Nurs. 2011;20(5):345-57. [PubMed: 21385294]
73. Wyman PA, Brown CH, LoMurray M, et al. An outcome evaluation of the Sources of Strength suicide prevention program delivered by adolescent peer leaders in high schools. Am J Public Health. 2010;100(9):1653-61. [PMC free article: PMC2920978] [PubMed: 20634440]
74. Druss BG, Zhao L, von Esenwein SA, et al. The Health and Recovery Peer (HARP) Program: a peer-led intervention to improve medical self-management for persons with serious mental illness. Schizophr Res. 2010;118(1-3):264-70. [PMC free article: PMC2856811] [PubMed: 20185272]
75. Becker CB, Wilson C, Williams A, Kelly M, McDaniel L, Elmquist J. Peer-facilitated cognitive dissonance versus healthy weight eating disorders prevention: A randomized comparison. Body Image. 2010;7(4):280-8. [PubMed: 20638351]
76. Vaughan CA, Foshee VA, Ennett ST, Vaughan CA, Foshee VA, Ennett ST. Protective effects of maternal and peer support on depressive symptoms during adolescence. J Abnorm Child Psychol. 2010;38(2):261-272. [PMC free article: PMC4029412] [PubMed: 19908140]
77. McVey GL, Kirsh G, Maker D, et al. Promoting positive body image among university students: a collaborative pilot study. Body Image. 2010;7(3):200-204. [PubMed: 20227934]
78. Dennis CL, Hodnett E, Kenton L, et al. Effect of peer support on prevention of postnatal depression among high risk women: multisite randomised controlled trial. BMJ. 2009;338():a3064. [PMC free article: PMC2628301] [PubMed: 19147637]
79. Walker RL, Ashby J, Hoskins OD, Greene FN. Peer-support suicide prevention in a non-metropolitan U.S. community. Adolescence. 2009;44(174):335-46. [PubMed: 19764270]
80. Dennis CL, Hodnett E, Kenton L, et al. Effect of peer support on prevention of postnatal depression among high risk women: multisite randomised controlled trial. Bmj. 2009;338. PM:CN-00666375 [PMC free article: PMC2628301] [PubMed: 19147637]
81. Black Becker C, Bull S, Smith LM, Ciao AC. Effects of being a peer-leader in an eating disorder prevention program: can we further reduce eating disorder risk factors?. Eat. 2008;16(5):444-59. [PubMed: 18821367]
82. Becker CB, Bull S, Schaumberg K, Cauble A, Franco A. Effectiveness of peer-led eating disorders prevention: a replication trial. J Consult Clin Psychol. 2008;76(2):347-54. [PubMed: 18377130]
83. Rowe M, Bellamy C, Baranoski M, et al. A peer-support, group intervention to reduce substance use and criminality among persons with severe mental illness. Psychiatr Serv. 2007;58(7):955-61. [PubMed: 17602012]
84. Sidhu R, Passmore A, Baker D. The effectiveness of a peer support camp for siblings of children with cancer. Pediatr Blood Cancer. 2006;47(5):580-8. [PubMed: 16317733]

Irrelevant Intervention (n = 50)

1. Kruzan KP, Whitlock J, Bazarova NN, Bhandari A, Chapman J. Use of a Mobile Peer support App Among Young People With Nonsuicidal Self-injury: Small-scale Randomized Controlled Trial. JMIR Form Res. 2022;6(1). [PMC free article: PMC8787664] [PubMed: 35006076]
2. Kruzan KP, Whitlock J, Bazarova NN. Examining the relationship between the use of a mobile peer-support app and self-injury outcomes: longitudinal mixed methods study. JMIR mental health. 2021;8(1) (no pagination)():. [PMC free article: PMC7878111] [PubMed: 33507154]
3. Ahorsu DK, Sanchez Vidana DI, Lipardo D, et al. Effect of a peer-led intervention combining mental health promotion with coping-strategy-based workshops on mental health awareness, help-seeking behavior, and wellbeing among university students in Hong Kong. Int J Ment Health Syst. 2021;15(1) (no pagination)():. [PMC free article: PMC7796456] [PubMed: 33422098]
4. Chory A, Callen G, Nyandiko W, et al. A Pilot Study of a Mobile Intervention to Support Mental Health and Adherence Among Adolescents Living with HIV in Western Kenya. Aids Behav. 2021;22():22. [PMC free article: PMC8295454] [PubMed: 34292429]
5. Muehlenkamp JJ, Quinn-Lee L. Effectiveness of a peer-led gatekeeper program: A longitudinal mixed-method analysis. J Am Coll Health. 2021;():1-10. [PubMed: 33759720]
6. Rodriguez M, Eisenlohr-Moul TA, Weisman J, Rosenthal MZ. The Use of Task Shifting to Improve Treatment Engagement in an Internet-Based Mindfulness Intervention Among Chinese University Students: Randomized Controlled Trial. JMIR Form Res. 2021;5(10):e25772. [PMC free article: PMC8552103] [PubMed: 34643532]
7. Tambag H. Examination of nursing students' anxiety levels related to clinical practice with respect to peer support. Perspect Psychiatr Care. 2021;57(3):1114-1119. [PubMed: 33111380]
8. Alvarez-Jimenez M, Koval P, Schmaal L, et al. The Horyzons project: a randomized controlled trial of a novel online social therapy to maintain treatment effects from specialist first-episode psychosis services. World Psychiatry. 2021;20(2):233-243. [PMC free article: PMC8129860] [PubMed: 34002511]
9. Hughes S, Rondeau M, Shannon S, et al. A Holistic Self-learning Approach for Young Adult Depression and Anxiety Compared to Medication-Based Treatment-As-Usual. Community Ment Health J. 2021;57(2):392-402. [PubMed: 32577998]
10. Davis M. 14.1 Peer academic supports for college students with mental illness: pilot randomized controlled trial. J Am Acad Child Adolesc Psychiatry. 2021;60(10):S278-S279.
11. Keeler LA, Skidmore B, Leenstra T, MacDonald JR, Stewart D. Treating University Students’ Depression using Physical Activity with Peers: Two Field-Based Quasi-Experiments Grounded in the Self-Determination Theory. J Coll Stud Psychother. 2021;35(3):205-223.
12. Drysdale MTB, McBeath ML, Callaghan SA. The feasibility and impact of online peer support on the well-being of higher education students. J Ment Health Train Educ Pract. 2021.
13. Ghaderi A, Stice E, Andersson G, Eno Persson J, Allzen E. A randomized controlled trial of the effectiveness of virtually delivered Body Project (vBP) groups to prevent eating disorders. J Consult Clin Psychol. 2020;88(7):643-656. [PubMed: 32551736]
14. Alvarez-Jimenez M, Rice S, D'Alfonso S, et al. A novel multimodal digital service (moderated online social therapy+) for help-seeking young people experiencing mental ill-health: Pilot evaluation within a national youth e-mental health service. J Med Internet Res. 2020;22(8) (no pagination)():. [PMC free article: PMC7453330] [PubMed: 32788151]
15. Blakeslee JE, Powers LE, Geenen S, et al. Evaluating the My Life self-determination model for older youth in foster care: Establishing efficacy and exploring moderation of response to intervention. Child Youth Serv Rev. 2020;119():. [PMC free article: PMC7544005] [PubMed: 33041412]
16. Chyzzy B, Nelson LE, Stinson J, Vigod S, Dennis CL. Adolescent Mothers' Perceptions of a Mobile Phone-Based Peer Support Intervention. Can J Nurs Res. 2020;52(2):129-138. [PubMed: 32036679]
17. Vanobberghen F, Weiss HA, Fuhr DC, et al. Effectiveness of the Thinking Healthy Programme for perinatal depression delivered through peers: Pooled analysis of two randomized controlled trials in India and Pakistan. J Affect Disord. 2020;265():660-668. [PMC free article: PMC7042347] [PubMed: 32090783]
18. Campbell A, Ridout B, Amon K, Navarro P, Collyer B, Dalgleish J. A Customized Social Network Platform (Kids Helpline Circles) for Delivering Group Counseling to Young People Experiencing Family Discord That Impacts Their Well-Being: Exploratory Study. J Med Internet Res. 2019;21(12):e16176. [PMC free article: PMC6942185] [PubMed: 31859671]
19. Sommer J, Gill KH, Stein-Parbury J, Cronin P, Katsifis V. The Role of Recovery Colleges in Supporting Personal Goal Achievement. Psychiatr Rehabil J. 2019;42(4):394-400. [PubMed: 31135174]
20. Olowokere AE, Okanlawon FA. Improving vulnerable school children's psychosocial health outcomes through resilience-based training and peer-support activities: A comparative prospective study. Vulnerable Child Youth Stud. 2018;13(4):291-304.
21. Pickering TA, Wyman PA, Schmeelk-Cone K, et al. Diffusion of a Peer-Led Suicide Preventive Intervention Through School-Based Student Peer and Adult Networks. Front Psychiatry. 2018;9 (no pagination)():. [PMC free article: PMC6249330] [PubMed: 30498462]
22. Parikh SV, Taubman DS, Antoun C, et al. The Michigan peer-to-Peer depression awareness program: School-Based prevention to address depression among teens. Psychiatr Serv. 2018;69(4)():487-491. [PubMed: 29493416]
23. Byrom N. An evaluation of a peer support intervention for student mental health. J Ment Health. 2018;27(3)():240-246. [PubMed: 29451411]
24. Eickman L, Betts J, Pollack L, Bozsik F, Beauchamp M, Lundgren J. Randomized controlled trial of REbeL: A peer education program to promote positive body image, healthy eating behavior, and empowerment in teens. Eat. 2018;26(2):127-142. [PubMed: 29072551]
25. Rice S, Gleeson J, Davey C, et al. Moderated online social therapy for depression relapse prevention in young people: pilot study of a 'next generation' online intervention. Early Interv Psychiatry. 2018;12(4):613-625. [PubMed: 27311581]
26. Chiu I, Graham JA. The effect of a peer-based personal stories intervention on focus of anxiety and social distance towards people with mental illness. J Coll Stud Dev. 2017;58(1):101-107.
27. Rohde P, Stice E, Shaw H, Gau JM, Ohls OC. Age effects in eating disorder baseline risk factors and prevention intervention effects. International Journal of Eating Disorders. 2017;50(11):1273-1280. [PMC free article: PMC5745064] [PubMed: 28861902]
28. Arora PG, Wheeler LA, Fisher S, Barnes J. A prospective examination of anxiety as a predictor of depressive symptoms among Asian American early adolescent youth: The role of parent, peer, and teacher support and school engagement. Cultur Divers Ethni Minor Psychol. 2017;23(4):541-550. [PubMed: 28604022]
29. Simmons MB, Batchelor S, Dimopoulos-Bick T, Howe D. The Choice Project: Peer Workers Promoting Shared Decision Making at a Youth Mental Health Service. Psychiatr Serv. 2017;68(8):764-770. [PubMed: 28457208]
30. Stice E, Rohde P, Shaw H, Gau JM. Clinician-led, peer-led, and internet-delivered dissonance-based eating disorder prevention programs: Acute effectiveness of these delivery modalities. J Consult Clin Psychol. 2017;85(9):883-895. [PMC free article: PMC5578897] [PubMed: 28425735]
31. Wilksch SM, Paxton SJ, Byrne SM, Austin SB, O'Shea A, Wade TD. Outcomes of three universal eating disorder risk reduction programs by participants with higher and lower baseline shape and weight concern. International Journal of Eating Disorders. 2017;50(1):66-75. [PubMed: 27768806]
32. McConnell EA, Birkett M, Mustanski B. Families Matter: Social Support and Mental Health Trajectories Among Lesbian, Gay, Bisexual, and Transgender Youth. J Adolesc Health. 2016;59(6):674-680. [PMC free article: PMC5217458] [PubMed: 27707515]
33. Kilpela LS, Blomquist K, Verzijl C, Wilfred S, Beyl R, Becker CB. The body project 4 all: A pilot randomized controlled trial of a mixed-gender dissonance-based body image program. International Journal of Eating Disorders. 2016;49(6):591-602. [PMC free article: PMC5365075] [PubMed: 27188688]
34. Bohleber L, Crameri A, Eich-Stierli B, Telesko R, von Wyl A. Can We Foster a Culture of Peer Support and Promote Mental Health in Adolescence Using a Web-Based App? A Control Group Study. JMIR mental health. 2016;3(3):e45. [PMC free article: PMC5074648] [PubMed: 27663691]
35. Greif R, Becker CB, Hildebrandt T. Reducing eating disorder risk factors: A pilot effectiveness trial of a train-the-trainer approach to dissemination and implementation. International Journal of Eating Disorders. 2015;48(8):1122-31. [PubMed: 26281792]
36. Morris RR, Schueller SM, Picard RW. Efficacy of a Web-based, crowdsourced peer-to-peer cognitive reappraisal platform for depression: randomized controlled trial. J Med Internet Res. 2015;17(3):e72. [PMC free article: PMC4395771] [PubMed: 25835472]
37. Farrell CT, Bolland JM, Cockerham WC. The role of social support and social context on the incidence of attempted suicide among adolescents living in extremely impoverished communities. J Adolesc Health. 2015;56(1):59-65. [PubMed: 25438969]
38. Stice E, Marti CN, Cheng ZH. Effectiveness of a dissonance-based eating disorder prevention program for ethnic groups in two randomized controlled trials. Behav Res Ther. 2014;55():54-64. [PMC free article: PMC4014461] [PubMed: 24655465]
39. Rose K, Hawes DJ, Hunt CJ. Randomized controlled trial of a friendship skills intervention on adolescent depressive symptoms. J Consult Clin Psychol. 2014;82(3):510-20. [PubMed: 24491074]
40. Elafros MA, Mulenga J, Mbewe E, et al. Peer support groups as an intervention to decrease epilepsy-associated stigma. Epilepsy and Behavior. 2013;27(1)():188-192. [PMC free article: PMC3602129] [PubMed: 23454914]
41. Kamalifard M, Yavarikia P, Babapour Kheiroddin J, Salehi Pourmehr H, Iraji Iranagh R. The effect of peers support on postpartum depression: a single-blind randomized clinical trial. J Caring Sci. 2013;2(3):237-44. [PMC free article: PMC4134152] [PubMed: 25276732]
42. Field T, Diego M, Delgado J, Medina L. Peer support and interpersonal psychotherapy groups experienced decreased prenatal depression, anxiety and cortisol. Early Hum Dev. 2013;89(9):621-4. [PMC free article: PMC3742661] [PubMed: 23727060]
43. Stice E, Rohde P, Durant S, Shaw H, Wade E. Effectiveness of peer-led dissonance-based eating disorder prevention groups: results from two randomized pilot trials. Behav Res Ther. 2013;51(4-5):197-206. [PMC free article: PMC3917500] [PubMed: 23419888]
44. Horgan A, McCarthy G, Sweeney J. An Evaluation of an Online Peer Support Forum for University Students With Depressive Symptoms. Arch Psychiatr Nurs. 2013;27(2):84-89. [PubMed: 23540518]
45. Thompson C, Russell-Mayhew S, Saraceni R. Evaluating the effects of a peer-support model: reducing negative body esteem and disordered eating attitudes and behaviours in grade eight girls. Eat. 2012;20(2):113-26. [PubMed: 22364343]
46. Lindenberg K, Moessner M, Harney J, McLaughlin O, Bauer S. E-health for individualized prevention of eating disorders. Clinical Practice and Epidemiology in Mental Health. 2011;7():74-83. [PMC free article: PMC3115599] [PubMed: 21687562]
47. Kumakech E, Cantor-Graae E, Maling S, Bajunirwe F. Peer-group support intervention improves the psychosocial well-being of AIDS orphans: cluster randomized trial. Soc Sci Med. 2009;68(6):1038-43. [PubMed: 19167144]
48. Houlston C, Smith PK. The impact of a peer counselling scheme to address bullying in an all-girl London secondary school: a short-term longitudinal study. Br J Educ Psychol. 2009;79(Pt 1):69-86. [PubMed: 18435867]
49. Specht DM. The effect of supportive strategies on computer anxiety and computer self-efficacy in nursing students. . 2008;():173 p-173 p.
50. Nash KA. Implementation and evaluation of the Empower Youth Program. Journal of Holistic Nursing. 2007;25(1):26-36. [PubMed: 17325311]

Irrelevant Study Design or Format (n = 60)

1. Ma Q, Parisi JM, Joo JH, Gallo JJ. Singapore young adults' perception of mental health help-seeking from mental health professionals and peer supporters. Asian J Psychiatr. 2021;61 (no pagination)():. [PubMed: 34004461]
2. Ojeda VD, Jones N, Munson MR, Berliant E, Gilmer TP. Roles of peer specialists and use of mental health services among youth with serious mental illness. Early Interv Psychiatry. 2021;15(4)():914-921. [PMC free article: PMC9305632] [PubMed: 32888260]
3. Suresh R, Karkossa Z, Richard J, Karia M. Program evaluation of a student-led peer support service at a Canadian university. Int J Ment Health Syst. 2021;15(1) (no pagination)():. [PMC free article: PMC8165510] [PubMed: 34059083]
4. Tinago CB, Frongillo EA, Warren AM, et al. Development and assessment of feasibility of a community-based peer support intervention to mitigate social isolation and stigma of adolescent motherhood in Harare, Zimbabwe. Pilot and Feasibility Studies. 2021;7(1) (no pagination)():. [PMC free article: PMC8127315] [PubMed: 34001288]
5. Arenas DL, Viduani AC, Bassols AMS, Hauck S. Peer support intervention as a tool to address college students' mental health amidst the COVID-19 pandemic. Int J Soc Psychiatry. 2021;67(3)():301-302. [PubMed: 32883124]
6. Ojeda VD, Munson MR, Jones N, Berliant E, Gilmer TP. The Availability of Peer Support and Disparities in Outpatient Mental Health Service Use Among Minority Youth with Serious Mental Illness. Adm Policy Ment Health. 2021;48(2)():290-298. [PMC free article: PMC7870605] [PubMed: 32728991]
7. Andalibi N, Flood MK. Considerations in designing digital peer support for mental health: interview study among users of a digital support system (buddy project). JMIR mental health. 2021;8(1) (no pagination)():. [PMC free article: PMC7813628] [PubMed: 33393909]
8. Ellis AE, Martino S, Simiola V, Mackintosh MA, Bellamy C, Cook JM. Study design and interventions for a peer-delivered motivational interviewing group treatment for sexual and gender minority male sexual trauma survivors. Contemp Clin Trials. 2021;111():106597. [PubMed: 34653650]
9. Wogrin C, Willis N, Mutsinze A, et al. It helps to talk: A guiding framework (TRUST) for peer support in delivering mental health care for adolescents living with HIV. PLoS ONE [Electronic Resource]. 2021;16(3):e0248018. [PMC free article: PMC7928463] [PubMed: 33657185]
10. Gillard S, Banach N, Barlow E, et al. Developing and testing a principle-based fidelity index for peer support in mental health services. Soc Psychiatry Psychiatr Epidemiol. 2021;56(10):1903-1911. [PMC free article: PMC8429155] [PubMed: 33606048]
11. Birrell L, Furneaux-Bate A, Chapman C, Newton NC. A Mobile Peer Intervention for Preventing Mental Health and Substance Use Problems in Adolescents: Protocol for a Randomized Controlled Trial (The Mind Your Mate Study). JMIR Res Protoc. 2021;10(7):e26796. [PMC free article: PMC8367112] [PubMed: 34328426]
12. Kaess M, Moessner M, Koenig J, et al. Editorial Perspective: A plea for the sustained implementation of digital interventions for young people with mental health problems in the light of the COVID‐19 pandemic. Journal of Child Psychology & Psychiatry. 2021;62(7):916-918. [PMC free article: PMC8359353] [PubMed: 32924134]
13. Riana Lestari T, Adyas A, Karma A, et al. Model of social support for adolescent mental health with disabilities. Medico-Legal Update. 2020;20(1)():2317-2321.
14. Guerra C, Aguilera G, Lippians C, et al. Online Sexual Abuse and Symptomatology in Chilean Adolescents: The Role of Peer Support. J Interpers Violence. 2020;():886260520957685. [PubMed: 32907454]
15. Thomas AL, Brausch AM. Family and peer support moderates the relationship between distress tolerance and suicide risk in black college students. J Am Coll Health. 2020;():1-8. [PubMed: 32669061]
16. Singla DR, Ratjen C, Krishna RN, Fuhr DC, Patel V. Peer supervision for assuring the quality of non-specialist provider delivered psychological intervention: Lessons from a trial for perinatal depression in Goa, India. Behav Res Ther. 2020;130():103533. [PubMed: 31870496]
17. Simmons MB, Grace D, Fava NJ, et al. The Experiences of Youth Mental Health Peer Workers over Time: A Qualitative Study with Longitudinal Analysis. Community Ment Health J. 2020;56(5):906-914. [PubMed: 31970578]
18. Cavazos-Rehg PA, Fitzsimmons-Craft EE, Krauss MJ, et al. Examining the self-reported advantages and disadvantages of socially networking about body image and eating disorders. International Journal of Eating Disorders. 2020;53(6):852-863. [PMC free article: PMC8135099] [PubMed: 32359127]
19. Kachaturoff M, Caboral-Stevens M, Gee M, Lan VM. Effects of peer-mentoring on stress and anxiety levels of undergraduate nursing students: An integrative review. J Prof Nurs. 2020;36(4):223-228. [PubMed: 32819548]
20. Bernays S, Tshuma M, Willis N, et al. Scaling up peer-led community-based differentiated support for adolescents living with HIV: keeping the needs of youth peer supporters in mind to sustain success. J Int AIDS Soc. 2020;23 Suppl 5():e25570. [PMC free article: PMC7459167] [PubMed: 32869532]
21. Rath S, Prost A, Samal S, et al. Community youth teams facilitating participatory adolescent groups, youth leadership activities and livelihood promotion to improve school attendance, dietary diversity and mental health among adolescent girls in rural eastern India: protocol for a cluster-randomised controlled trial. Trials. 2020;21(1):52. [PMC free article: PMC6950906] [PubMed: 31915039]
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Appendix 4. Semi-Structured Consultation Interview Guide

Note that this appendix has not been copy-edited.

Appendix 5. List of Key Informant Organizations and Peer Support Programs

Note that this appendix has not been copy-edited.

Table 34

List of Key Informant Organizations and Peer Support Programs.

Appendix 6. Summary of Included Studies

Table 35

Summary of Included Studies From Literature.

Appendix 7. Summary of Program Evaluation Reports From Stakeholders

Table 36

Summary of Program Evaluation Reports From Stakeholders.

Appendix 8. Summary of Program Evaluation Methods From Stakeholder Consultations

Table 37

Summary of Program Evaluation Methods From Stakeholder Consultations.

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