1. From the Framingham Heart Study, Framingham, Mass; Division of Cardiology (T.J.W.), Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Mass; Department of Mathematics and Statistics (M.G.L., M.J.K.), Boston University, Boston, Mass; National Heart, Lung, and Blood Institute (D.L.), Bethesda, Md; and Preventive Medicine and Cardiology Sections (D.L., E.J.B., R.S.V.), Boston University School of Medicine, Boston, Mass.