1. From the Departments of Epidemiology (S.V., P.M., L.A.B., P.K.W., J.H.) and Biostatistics (J.J.L.), Tulane University School of Public Health and Tropical Medicine; the Department of Medicine (V.B., P.K.W., J.H.), Tulane University School of Medicine; and the Veterans Administration Medical Center (V.B.), New Orleans, La.