[1] Univ Michigan, Dept Internal Med, Ann Arbor, MI 48109 USA
[2] Henry Ford Hlth Syst, Dept Internal Med, Detroit, MI USA
[3] Univ Michigan, Dept Stat, Ann Arbor, MI 48109 USA
[4] Amer Coll Physicians, Res Ctr, Philadelphia, PA USA
[5] Vet Affairs Ctr Clin Management Res, Ann Arbor, MI USA
[6] Vet Affairs Med Ctr, Ambulatory Care, Ann Arbor, MI USA