[1] Univ Lausanne, Div Gen Internal Med, Lausanne, Switzerland
[2] Hosp Ramon & Cajal, Resp Dept, E-28034 Madrid, Spain
[3] VA Ctr Hlth Equ Res & Promot, Pittsburgh, PA USA
[4] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Biostat, Pittsburgh, PA 15261 USA
[5] Univ Pittsburgh, Dept Med, Div Gen Internal Med, Pittsburgh, PA 15261 USA