[1] Harvard Univ, Sch Publ Hlth, Dept Hlth Policy & Management, Boston, MA 02115 USA
[2] Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA
[3] Brigham & Womens Hosp, Dept Med, Div Cardiovasc, Boston, MA 02115 USA
[4] Vet Affairs Boston Healthcare Syst, Dept Med, Cardiol & Vasc Med Sect, Boston, MA USA
[5] Brigham & Womens Hosp, Dept Med, Div Gen Internal Med, Boston, MA 02115 USA
[6] Vet Affairs Boston Healthcare Syst, Dept Med, Gen Internal Med Sect, Boston, MA USA