[1] Harvard Univ, Massachusetts Gen Hosp, Sch Med, Med Practices Evaluat Ctr,Med Serv, Boston, MA 02114 USA
[2] Harvard Univ, Massachusetts Gen Hosp, Sch Med, Gen Med Div,Med Serv, Boston, MA 02114 USA
[3] Maine Med Assessment Fdn, Augusta, ME USA
[4] Univ Washington, Ctr Cost & Outcomes Res, Seattle, WA 98195 USA
[5] Univ Washington, Dept Med, Seattle, WA 98195 USA
[6] Univ Washington, Dept Hlth Serv, Seattle, WA 98195 USA