[1] Calif Pacific Med Ctr, Res Inst, San Francisco, CA USA
[2] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA 94143 USA
[3] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Epidemiol, Pittsburgh, PA 15260 USA
[4] VA Hlth Care Syst, Ctr Chron Dis Outcomes Res, Minneapolis, MN USA
[5] Univ Minnesota, Dept Med, Minneapolis, MN 55455 USA
[6] Univ Minnesota, Div Epidemiol & Community Hlth, Minneapolis, MN 55455 USA
[7] Pk Nicollet Clin, St Louis Pk, MN USA
[8] Univ Minnesota, Div Hlth Policy & Management, Minneapolis, MN USA