[1] Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Div Gen Internal Med & Hlth Serv Res, Los Angeles, CA 90095 USA
[2] Ctr Dis Control & Prevent, Atlanta, GA USA
[3] Kaiser Permanente, Div Res, Oakland, CA USA
[4] Univ N Carolina, Dept Hlth Policy & Adm, Chapel Hill, NC USA
[5] Durham VAMC, Ctr Hlth Serv Res Primary Care, Durham, NC USA
[6] Birmingham VA Med Ctr, Deep S Ctr Effectiveness, Birmingham, AL USA
[7] Univ Alabama Birmingham, Dept Prevent Med, Birmingham, AL USA
[8] Johns Hopkins Univ, Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA
[9] Univ Med & Dent New Jersey, New Brunswick, NJ USA
[10] Pacific Hlth Res Inst, Honolulu, HI USA
[11] Univ Michigan, Dept Med, Ann Arbor, MI 48109 USA
[12] Univ Michigan, Dept Obstet Gynecol, Ann Arbor, MI 48109 USA