From the Division of General Internal Medicine (N.M.M., L.J.A.) and the Welch Center for Prevention, Epidemiology, and Clinical Research (N.M.M., N.-Y.W., L.J.A.), The Johns Hopkins University School of Medicine, Baltimore, Md; and Department of Epidemiology (L.J.A.), The Johns Hopkins University Bloomberg School of Public Health, Baltimore, Md. (2009-04-21時点)