1. From the Division of Research, Kaiser Permanente Medical Care Program (Northern California), Oakland, Calif (A.S.G., K.A.P., J.V.S.); the Department of Epidemiology and Biostatistics, University of California at San Francisco (A.S.G.); and the General Medicine Division, Clinical Epidemiology Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Mass (E.M.H., L.H.B., L.E.H., Y.C., D.E.S.).