Introduction

Health centers are community-based clinics that offer access to primary care to underserved communities (1,2). Health centers are either federally qualified health centers, which receive federal funding from the Health Resources and Services Administration (HRSA), or federally qualified health center look-alikes, which meet HRSA requirements but do not receive HRSA funding (3). Health centers provide various services to patients, including medical, vision, and dental services (4,5). Preventive services, including cancer screenings, immunizations, and prenatal care are offered at health centers and represent a significant percentage of visits to health centers (5). In 2022, health centers provided care to 30.5 million patients (6).

Adults and females represented the highest percentages of patients visiting health centers (4). Patients age 65 and older represent the fastest growing age group of adult visits to health centers, with a 147% increase from 2010 through 2020 (7). This report examines adult visit rates by age and sex along with percentage of visits by selected demographics (age, sex, and marital status). It also examines major disease categories and selected reasons for visits by age and sex using data from the 2022 National Ambulatory Medical Care Survey (NAMCS) Health Center (HC) Component.

Methods

Data for this report are from the 2022 NAMCS HC Component. The NAMCS HC Component includes visit data from electronic health records (EHRs) from federally qualified health centers and federally qualified health center look-alikes (3) from all 50 U.S. states and the District of Columbia. Health centers that were fully or partially funded by HRSA were included. Health centers were deemed ineligible for NAMCS if they 1) did not have an EHR system; 2) did not provide healthcare services to the general U.S. population or only provided care to specific institutionalized populations such as prisoners, nursing home residents, students, etc.; 3) provided only dental services; or 4) were located on a military installation or outside of the 50 U.S. states and the District of Columbia. Health centers were sampled for the NAMCS HC Component from a database provided to the National Center for Health Statistics by HRSA that contained a list of all health centers in the United States. Before drawing the sample, all ineligible health centers were removed, which included 64 health centers that did not meet the inclusion criteria described previously and 149 health centers that were included in the 2021 sample. Additional sampling design details for the NAMCS HC Component are described in detail elsewhere (8). In the 2022 NAMCS HC Component, 64 health centers participated out of 255 that were contacted to participate, resulting in a response rate of 25.1%. Participating health centers included 26 health centers that previously participated in the 2021 NAMCS HC Component and 38 health centers newly participating in 2022. Collectively, these centers submitted data for all visits that occurred in these centers during 2022, which included more than 5.6 million visits (unweighted).

To submit visit data from their EHR systems for the NAMCS HC Component, health centers could use either of two approaches. In the first, a health center would submit data via the “HL7 CDA R2 Implementation Guide: National Health Care Surveys, Release 1, DSTU Release 1.2 – US Realm” (9). This guide serves as an electronic template for EHR systems and allows a center to submit the data requested through their EHR system in the required format, for the specified variables requested. If a sampled health center was unable to submit data through the Implementation Guide, another option for submitting data was to send a custom data extract from their EHR system. Through these submission options, patient demographic characteristics and visit information such as diagnoses, procedures, medications, laboratory results, and vitals were collected. Once these data were collected, several processing steps were performed. Patient identifiers were captured, which allowed the National Center for Health Statistics to identify any duplicate records (that is, visits by the same patient on the same day at the same health center) and create patient-level records that could link to outside sources. Once identified, the duplicate records were collapsed into a single record per patient, per day at a given health center. These collapsed daily records are referred to as visits in the NAMCS HC Component.

Diagnoses were captured in the EHR data using three different medical coding systems: International Classification of Diseases, Ninth Revision, Clinical Modification (ICD–9–CM), International Classification of Diseases, 10th Revision, Clinical Modification (ICD–10–CM), and Systematized Medical Nomenclature for Medicine–Clinical Terminology or SNOMED–CT. Where possible, ICD–9–CM and SNOMED codes were translated into ICD–10–CM codes. In this report, ICD–10–CM codes were used to identify disease categories and reasons for visits.

Disease categories were identified using ICD–10–CM chapter definitions. Reasons for visits were defined by combining multiple ICD–10–CM codes, including codes across multiple ICD–10–CM chapters. Some of these categories were based on categories used previously in presenting health center data (10). Code descriptions and associated labels are provided in Tables 2 and 3. Diagnoses presented in the tables and figures include all diagnoses contained in the medical record and may include historical diagnoses established before the current visit. Categories are not mutually exclusive; the same visit can be represented in multiple disease categories and reasons for visit. Moreover, the primary diagnosis for each visit could not be distinguished from other diagnoses on the visit record.

Four age groups are used in this report: 18–44, 45–54, 55–64, and 65 and older. When presenting reasons for visit, adults age 45 and older are presented together to increase statistical power and reliability. Despite this grouping, some of the estimates for older adults remain unreliable in Tables 2 and 3.

Marital status was categorized into four groups: married (including common law and domestic partners); divorced (also includes legally separated partners); not married; and widowed. These combined categories were based on previous literature suggesting similar health risks among these groups and on the access to health benefits for these groups (11,12).

Diagnoses and reasons for visits in Tables 2 and 3 were only assessed by age and sex. Due to small sample sizes leading to unreliable estimates, and considering the relationship between age and marital status, diagnoses and reasons for visits could not be divided (stratified) by age and marital status, so marital status was not included in the analysis.

To provide national estimates of health center visits, weighting was conducted to produce visit-level estimates, which account for sampling probabilities and nonresponse (13). For both diagnosis and marital status variables, some data were missing from all visits submitted by some of the participating health centers. In these instances, the visit weights were normalized to account for health centers that were excluded. Normalized weights were calculated according to the following formula: new weight = original weight • (sum of weights at all visits / sum of weights at included visits) (13).

Data analyses were performed using the statistical packages SAS version 9.4 (SAS Institute, Cary, N.C.) and SAS-callable SUDAAN version 11.0 (RTI International, Research Triangle Park, N.C.). Differences in the distribution of selected characteristics of health center visits were based on chi-square tests (p < 0.05). If a difference was found to be statistically significant, additional pairwise tests were performed. Statements of difference in paired estimates were based on two-tailed t tests with statistical significance at the p < 0.05 level. Terms such as “higher” or “lower” indicate that the differences were statistically significant. Lack of significant differences between some estimates could be due to low statistical power. Estimates were assessed for reliability using the National Center for Health Statistics data presentation standards for proportions and rates (14,15). Estimates that did not meet these standards are identified in the tables with an asterisk.

Results

Distribution of visits to health centers by patient age and sex

In 2022, there were an estimated 349.4 visits per 1,000 adults to health centers (Figure 1). The visit rate for women (444.9 visits per 1,000 women) was higher than the rate for men (248.8 visits per 1,000 men). Visit rates by age were 324.6 per 1,000 adults ages 18–44, 398.1 per 1,000 adults ages 45–54, 417.9 per 1,000 adults ages 55–64, and 315.9 per 1,000 adults age 65 and older. No significant differences were observed in these visit rates. When examining the percentage distribution of visits to health centers by sex, more visits were by women compared with men (65.2% and 34.8%, respectively) (Table 1). The percentage of visits by younger adults ages 18–44 (42.8%) was higher than the percentage of visits by adults ages 45–54 (17.8%), 54–64 (19.5%), and 65 and older (19.9%). The percentage of visits by adults who were not married was higher (48.2%) than the percentage of visits by married adults (37.6%), divorced adults (9.7%), and widowed adults (4.6%).

Figure 1

Health center visit rate for adults, by age group and sex: United States, 2022. ¹Significantly different from men. NOTES: Rates are based on a sample of 4,612,644 visits by adults to 64 health centers, representing an estimated 89.5 million adult visits (more...)

Table 1

Percentage of visits to health centers among adults, by age group, sex, and marital status: United States, 2022.

Percentages of visits to health centers by major disease category

Disease categories were defined using ICD–10–CM chapters. The three most frequently observed categories were: factors influencing health status and contact with health services (subsequently, factors influencing health status), which accounted for 41.8% of all visits; endocrine, nutritional, and metabolic disease (subsequently, endocrine diseases), which accounted for 29.1% of all visits; and symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified (subsequently, symptoms and signs), which accounted for 22.0% of all visits (Table 2). Other frequently observed disease categories, present in at least 10% of all health center visits, included mental, behavioral and neurodevelopmental disorders (subsequently, mental disorders) (21.6%); diseases of the circulatory system (subsequently, circulatory diseases) (17.8%); diseases of the musculoskeletal and connective tissue (subsequently, musculoskeletal diseases) (14.5%); diseases of the digestive system (subsequently, digestive diseases) (11.4%); and diseases of the respiratory system (subsequently, respiratory diseases), which includes COVID-19 and vaping-related disorders (10.8%). Similar distributions of these categories were found among men and women.

Table 2

Percentage of visits to health centers among adults, by disease category, age group, and sex: United States, 2022.

Among adults ages 18–44, two disease categories (excluding factors influencing health and symptoms and signs) included more than 10% of health center visits: mental disorders (24.5%) and endocrine diseases (20.1%). Among adults ages 45–54, the most frequently observed disease categories at health center visits included endocrine diseases (32.9%), mental disorders (21.9%), circulatory diseases (19.2%), musculoskeletal diseases (16.2%), digestive diseases (12.5%), and respiratory diseases (10.8%). Among adults ages 55–64, the most frequently observed disease categories at health center visits included endocrine diseases (36.4%), circulatory diseases (26.3%), mental disorders (21.1%), musculoskeletal diseases (19.0%), digestive diseases (12.8%), respiratory diseases (12.1%), and diseases of the nervous system (10.4%). Finally, among adults age 65 and older, the most frequent disease categories at health center visits included endocrine diseases (38.4%), circulatory diseases (32.7%), musculoskeletal diseases (21.4%), mental disorders (15.3%), digestive diseases (13.6%), respiratory diseases (12.8%), diseases of the genitourinary system (12.5%), and diseases of the nervous system (10.3%).

Percentages of visits to health centers by selected reasons for visit

Health center visits were further investigated by grouping ICD–10–CM codes into categories that describe the reason for the visit, including disease-related, symptom-related, screenings, examinations, immunizations, maternal and reproductive health-related (subsequently, reproduction related), injury-related, and potential health hazards related to socioeconomic and psychological circumstances (subsequently, social determinants of health-related) (Figure 2, Table 3). The same visit could include one or many of the previously mentioned reasons. Disease-related reasons were the most frequently observed, accounting for 61.4% of visits, followed by symptom-related reasons, accounting for 22.0% of health center visits. A screening occurred at 12.6% of health center visits, an examination at 10.2% of visits, and an immunization at 6.7% of visits. Injuries were diagnosed at 3.2% of health center visits. Social determinants of health were listed as a reason for visit at 2.0% of health center visits. Men and women showed a similar distribution. In examining the distribution of reasons for visit by age group, a higher percentage of health center visits by adults age 45 and older than younger adults included a disease- or symptom-related reason for visit. Women ages 18–44 had a higher percentage of reproduction-related visits compared with women age 45 and older (19.1% and 0.7%, respectively).

Figure 2

Percentage of visits to health centers among adults, by selected reason for visit: United States, 2022. ¹Significantly different from all other categories. ²Significantly higher than injury- and social determinants of health-related visits.

Table 3

Percentage of visits to health centers among adults, by selected reason for visit, age group, and sex: United States, 2022.

Discussion

This report presents nationally representative estimates of visits by adults to health centers in the United States during 2022. The overall rate of health center visits among adults was 349.4 visits per 1,000 adults. The visit rate for women was higher than the rate for men. Adults who were not married represented the highest percentage of adults who visited health centers. Considering the relationship between age and marital status (16), the Technical Notes Table shows the distribution of visits by age group and sex by marital status. As expected, the distribution of visits by marital status varied by age, with a higher percentage of visits by not-married adults among those ages 18–44, and a higher percentage of visits by married adults among those age 65 and older. Research has found that marital status could affect healthcare use (17) and suggests an association between marriage and better health outcomes (18). A recent study on a sample of Medicare beneficiaries showed that compared with unmarried beneficiaries, married beneficiaries had higher odds of having a recent outpatient visit and lower odds in the previous year of having an inpatient or skilled nursing facility stay (17). Examining patterns of healthcare use by marital status may help inform health centers to better serve the specific needs of their patients.

The distribution of disease categories among healthcare visits follows the distribution of these diseases in the general U.S. population, although adults visiting health centers have higher rates of chronic conditions compared with the general adult population (6). Endocrine diseases were the most frequently observed disease category at health centers. Diabetes is the most common endocrine disease, and in 2021, 38.1 million of adults had diabetes (19). Mental disorders also accounted for more than 20% of health center visits, and the percentage of health center visits that included a mental disorder decreased with age, from 24.5% of visits by adults ages 18–44 to 15.3% by adults age 65 and older. Hypertension is the most common circulatory disease, and the occurrence of hypertension increases with age (20). Similarly, at health center visits in this report, circulatory diseases increased with age from 6.5% of all visits by adults ages 18–44 to 32.7% of visits by adults age 65 and older. The number of disease categories accounting for more than 10% of visits at health centers increased with age. Only two disease categories accounted for more than 10% of visits by adults ages 18–44. This number increased to six categories for adults ages 45–54, seven categories for adults ages 55–64, and eight categories for adults age 65 and older.

Screenings and examinations were frequent reasons for health center visits. Data from HRSA have shown that clinical quality measures among health centers were improved in 2022 compared with previous years (4,5), including increasing screening rates for cancer, diabetes, tobacco, HIV, and depression. Among younger women ages 18–44, reproductive health-related visits were the reason for almost one in five health center visits.

Several limitations should be considered when interpreting the results of this report. Data from this report should not be compared with NAMCS data collected before 2021 because of the substantial change in the data collection methodology. Before 2021, the U.S. Census Bureau collected the data using a computerized instrument developed by the National Center for Health Statistics. Data were abstracted from medical records, with a target of about 30 sampled visits per provider during a randomly assigned 1-week reporting period (21). Starting in 2021, the NAMCS HC Component collected visit data from EHRs on all visits from all providers at a sampled health center for the entire calendar year.

Data from this report should not be compared with 2022 data collected from HRSA (4,5). The NAMCS HC Component provides visit-level data, not patient-level data, making comparisons with HRSA data inaccurate. Also, this report includes all visits, whereas some types of encounters were excluded as visits by HRSA. For example, certain screenings, laboratory tests, or follow-up visits were excluded from HRSA counts (22). The visit rates from this report should be not compared with the rates that could be calculated from HRSA data. However, the distribution of visits by demographic characteristics collected with the NAMCS HC Component and the distribution of patients from HRSA data report similar percentages. According to HSRA data, 49.7% of adults who used health centers in 2022 were ages 18–44, 16.9% were ages 45–54, 17.1% were ages 55–64, and 16.4% were age 65 and older (4,5). The NAMCS HC Component shows that among adults, 42.8% of visits were by adults ages 18–44, 17.8% by adults ages 45–54, 19.5% by adults ages 55–64, and 19.9% by adults age 65 and older. Finally, due to a high level of absence (missingness), some variables of interest such as race and ethnicity, type of provider seen, or insurance status, were not used for this analysis.

Despite these limitations, this report presents nationally representative estimates of visits to health centers in the United States during 2022 and provides insights into differences in the use of health centers by sex, age, and marital status.

References

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National Association of Community Health Centers. Community health chartbook 2024: Analysis of 2022 UDS data. Available from: https://www​.nachc.org​/resource/community-health-center-chartbook/.

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U.S. Department of Health and Human Services, Health Resources and Services Administration. Table 3A: Patients by age and by sex assigned at birth. Available from: https://data​.hrsa.gov​/tools/data-reporting​/program-data/state​/OR/table?tableName=3A.

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National Association of Community Health Centers. Community health centers: Providers, partners and employers of choice. 2020. Available from: https://www​.nachc.org​/wp-content/uploads​/2023/07/Community-Health-Center-Chartbook-2023-2021UDS.pdf.

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Department of Health and Services, Health Resources and Services Administration. 2022 Uniform Data System Trends data brief. 2023.

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National Association of Community Health Centers. Community health center chartbook. Figure 1–12. 2023. Available from: https://www​.nachc.org​/wp-content/uploads​/2023/04/Community-Health-Center-Chartbook-July-2023-2021UDS.pdf.

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Williams SN, Ukaigwe J, Ward BW, Okeyode T, Shimizu IM. Sampling procedures for the collection of electronic health record data from federally qualified health centers, 2021–2022 National Ambulatory Medical Care Survey. National Center for Health Statistics. Vital Health Stat Series 2(203). 2023. DOI: 10.15620/cdc:127730. [CrossRef]

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Health Level Seven International (HL7). HL7 CDA R2 implementation guide: National Health Care Surveys (NHCS), release 1, DSTU release 1.2—US realm. Available from: https://www​.hl7.org/implement​/standards/product_brief​.cfm?product_id=385.

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Santo L, Okeyode T, Schappert SM. National Ambulatory Medical Care Survey—Community health centers: 2020 national summary tables. National Center for Health Statistics. 2022.

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Dhindsa DS, Khambhati J, Schultz WM, Tahhan AS, Quyyumi AA. Marital status and outcomes in patients with cardiovascular disease. Trends Cardiovasc Med 30(4):215–20. 2020. [PubMed: 31204239]

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Roth AR, Peng S. Non-spousal support, marital status, and mortality risk. J Aging Health 34(1):41–50. 2022. [PubMed: 34114491]

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National Center for Health Statistics. Research Data Center National Ambulatory Medical Care Survey Health Center Component 2022 restricted use file data dictionary. 2023. Available from: https://www​.cdc.gov/rdc​/data/b1/2022-NAMCS-HCC-RDC-Data-Dictionary-508.pdf.

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Parker JD, Talih M, Malec DJ, Beresovsky V, Carroll M, Gonzalez JF Jr., et al. National Center for Health Statistics data presentation standards for proportions. National Center for Health Statistics. Vital Health Stat 2(175). 2017.

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Parker JD, Talih M, Irimata KE, Zhang G, Branum AM, Davis D, et al. National Center for Health Statistics data presentation standards for rates and counts. National Center for Health Statistics Vital Health Stat 2(200). 2023. DOI: 10.15620/cdc:124368. [CrossRef]

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Pandey KR, Yang F, Cagney KA, Smieliauskas F, Meltzer DO, Ruhnke GW. The impact of marital status on health care utilization among Medicare beneficiaries. Medicine (Baltimore). 98(12):e14871. 2019. [PubMed: 30896632]

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Technical Notes

Definitions of terms

Disease category—Based on the International Classification of Diseases, 10th Revision, Clinical Modification (ICD–10–CM) (23). Diagnosis chapters and the codes used to define them include:

• Certain infectious and parasitic diseases (A00–B99)
• Neoplasms (C00–D49)
• Diseases of the blood and blood-forming organs and certain disorders involving the mmune mechanism (D50–D89)
• Endocrine, nutritional, and metabolic disease (E00–E89)
• Mental, behavioral and neurodevelopmental disorders (F01–F99)
• Diseases of the nervous system (G00–G99)
• Diseases of the eye and adnexa (H00–H59)
• Diseases of the ear and mastoid process (H60–H95)
• Diseases of the circulatory system (I00–I99)
• Diseases of the respiratory system (includes COVID-19 and vaping-related disorders) (J00–J99, U070, U071, U099)
• Diseases of the digestive system (K00–K95)
• Diseases of the skin and subcutaneous tissue (L00–L99)
• Diseases of the musculoskeletal and connective tissue (M00–M99)
• Diseases of the genitourinary system (N00–N99)
• Pregnancy, childbirth and the puerperium (O00–O9A)
• Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified (R00–R99)
• Injury, poisoning and certain other consequences of external causes (S00–T88)
• External causes of morbidity (V00–Y99)
• Factors influencing health status and contact with health services (Z00–Z99)

Disease-related visit—A health center visit with any of the following codes in any of the diagnosis fields from ICD–10–CM (23): A00–N99, P00–Q99, U070, U071, U099.

Examination or observation visit—A health center visit with any of the following codes in any of the diagnosis fields from ICD–10–CM (23): Z00–Z09.

Social determinants of health-related visit— A health center visit with any of the following codes in any of the diagnosis fields from ICD–10–CM (23): Z55–Z65. These codes include encounters with people with potential health hazards related to socioeconomic and psychological circumstances and identify nonmedical factors that may influence a patient’s health status.

Immunization visit— A health center visit with the following code in any of the diagnosis fields from ICD–10–CM (23): Z23.

Injury-related visit—A health center visit with any of the following codes in any of the diagnosis fields from ICD–10–CM (23): S00–T88, V00–Y99.

Maternal and reproductive health-related visit— A health center visit among women with any of the following codes in any of the diagnosis fields from ICD–10–CM (23): Z3A, Z30–Z39, O00–O92.

Screening visit— A health center visit with any of the following codes in any of the diagnosis fields from ICD–10–CM (23): Z11–Z13.

Symptom-related visit— A health center visit with any of the following codes in any of the diagnosis fields from ICD–10–CM (23): R00–R99.

Visit rates— Calculated by dividing the number of visits by estimates of the U.S. civilian noninstitutionalized population (obtained from the U.S. Census Bureau’s Population Division) for selected characteristics including age group and sex.

Weight normalization— In some instances, certain health centers did not provide any information for any of their visits on diagnosis and marital status. Health centers were excluded if they were missing at least one of these variables at all visits. Consequently, visit weights for the remaining health centers were normalized to account for health centers that were excluded. Normalized weights were calculated according to the following formula:

New weight = original weight • (sum of weights at all visits / sum of weights at included visits).

Table

Percentage of visits to health centers among adults, by marital status, age group, and sex: United States, 2022.

National Center for Health Statistics

Brian C. Moyer, Ph.D., Director

Amy M. Branum, Ph.D., Associate Director for Science

Division of Health Care Statistics

Carol J. DeFrances, Ph.D., Director

Alexander Strashny, Ph.D., Associate Director for Science

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Santo L, Peters ZJ, Guluma L, Ashman JJ. Visits to health centers among adults, by selected characteristics: United States, 2022. National Health Statistics Reports; no 211. Hyattsville, MD: National Center for Health Statistics. 2024. DOI: https://dx.doi.org/10.15620/cdc/160502.