1. From the Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School (P.J.M., J.E.M., H.D.S., C.M.A., M.J.C., N.R.C., P.G., P.M.R., R.J.G.), Boston, Mass, and the Department of Preventive Medicine, Northwestern University Medical School (P.G.), Chicago, Ill.