The authors gratefully acknowledge Mary Butler, Ph.D., M.B.A., who served as Associate Editor; Leila Kahwati, M.D., M.P.H., at RTI International and Yulun Liu, Ph.D., and Yong Chen, Ph.D., of the University of Pennsylvania for their contributions to the qualitative comparative analysis; and the following individuals at ECRI Institute for their contributions to this project: Janice Kaczmarek, M.S., EPC Project Manager; Katherine Donahue; Gina Giradi, M.S.; Kristy McShea, M.S.L.I.S.; and Michael Phillips.

We also thank AHRQ Task Order Officers Aysegul Gozu, M.D., M.P.H., and David W. Niebuhr, M.D., M.P.H., M.Sc.; and the following individuals at National Heart, Lung, and Blood Institute: Janet M. DeJesus, M.S., and Michelle Freemer, M.D., M.P.H.

We appreciate the collaboration of our colleagues at the other EPCs preparing reports for NHLBI, and particularly thank Diana Sobieraj and others at the University of Connecticut EPC, who provided the table and references for minimally important differences in Appendix E.