[1] Univ Pittsburgh, Ctr Res Hlth Care, Div Gen Internal Med, Dept Med,Sch Med, Pittsburgh, PA 15213 USA
[2] Univ N Carolina, Gillings Sch Global Publ Hlth, Dept Hlth Policy & Management, Chapel Hill, NC USA
[3] Univ N Carolina, Cecil G Sheps Ctr Hlth Serv Res, Chapel Hill, NC USA
[4] Duke Univ, Med Ctr, Sch Med, Ctr Learning Hlth Care,Duke Clin Res Inst, Durham, NC 27710 USA
[5] Duke Univ, Med Ctr, Sch Med, Div Med Oncol, Durham, NC 27710 USA
[6] Phoenix VA Hlth Care Syst, Phoenix, AZ USA
[7] Durham Vet Affairs Med Ctr, Ctr Hlth Serv Res Primary Care, Durham, NC USA