1. Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, Massachusetts;
2. Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Harvard Medical School and Brigham and Women’s Hospital, Boston, Massachusetts;
3. Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts;
4. Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts;
5. Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts;
6. Centers for Disease Control and Prevention, Atlanta, Georgia