[1] Permanente Med Grp Inc, Div Res, Oakland, CA USA
[2] Kaiser Permanente, Div Res, Oakland, CA 94612 USA
[3] Patient Ctr Outcomes Res Inst, Washington, DC USA
[4] Permanente Med Grp Inc, Dept Med & Endocrinol, San Francisco, CA USA
[5] VA Ann Arbor Healthcare Syst, Ctr Clin Management Res, Ann Arbor, MI USA
[6] Univ Michigan, Sch Med, Div Gen Med, Ann Arbor, MI USA
[7] Massachusetts Gen Hosp, Mongan Inst Hlth Policy, Boston, MA 02114 USA
[8] Harvard Univ, Sch Med, Dept Hlth Care Policy, Boston, MA 02115 USA