1. From the Department of Epidemiology (A.E., L.H.K., A.B.N.), University of Pittsburgh, Pa; the Department of Neurology (O.L), University of Pittsburgh, Pa; the Department of Biostatistics (J.C.), University of Pittsburgh, Pa; the Department of General Medicine (K.M.), University of Pittsburgh, Pa; the Department of Medicine (M.C.), University of Vermont, Colchester, Vt; and the Department of Biostatistics (R.K.), University of Washington, Seattle, Wash.