1 Division of General Internal Medicine, Brigham and Women's Hospital, Boston, Massachusetts; Harvard Medical School, Boston, Massachusetts. Electronic address: lsamal@bwh.harvard.edu.
2 Department of Medicine, Faculty of Medicine & Dentistry; University of Alberta, Edmonton, Alberta, Canada.
3 Renal, Electrolyte, and Hypertension Division, Department of Medicine; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Center for Clinical Epidemiology and Biostatistics; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.