[1] BRIGHAM & WOMENS HOSP, DIV CARDIOVASC, BOSTON, MA 02115 USA
[2] BRIGHAM & WOMENS HOSP, DIV GEN MED, BOSTON, MA 02115 USA
[3] HARVARD UNIV, SCH MED, BOSTON, MA 02115 USA
[4] HARVARD UNIV, SCH PUBL HLTH, DEPT HLTH POLICY & MANAGEMENT, BOSTON, MA 02115 USA
[5] HARVARD UNIV, HARVARD COMMUNITY HLTH PLAN, INST HLTH RES, CAMBRIDGE, MA 02138 USA