From the Department of Medicine, Division of Nephrology (T.S., R.S.P.), and General Internal Medicine (L.J.A., E.R.M., M.J.K.), Department of Pediatrics, Division of Nephrology (R.S.P.), Johns Hopkins University School of Medicine; Department of Epidemiology (L.J.A., E.R.M., M.J.K., R.S.P.), Johns Hopkins Bloomberg School of Public Health; and the Welch Center for Prevention, Epidemiology and Clinical Research (L.J.A., E.R.M., M.J.K., R.S.P.), Baltimore, Md. (At 2008-12)