1 Division of Nephrology and Hypertension, Department of Medicine, University of North Carolina School of Medicine, University of North Carolina Kidney Center, Chapel Hill, North Carolina; jflythe@med.unc.edu.
2 Cecil G. Sheps Center for Health Services Research, University of North Carolina, Chapel Hill, North Carolina.
3 Division of Nephrology and Hypertension, Department of Medicine, University of North Carolina School of Medicine, University of North Carolina Kidney Center, Chapel Hill, North Carolina.
4 American Institutes for Research, Chapel Hill, North Carolina.
5 Department of Health Management and Policy, University of Michigan School of Public Health, Ann Arbor, Michigan.
6 Vancouver, Washington.
7 Punta Gorda, Florida; and.
8 Renal-Electrolyte and Hypertension Division, Department of Medicine, and.
9 Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania.