1. Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois;
2. Department of Medicine, Johns Hopkins University, Baltimore, Maryland;
3. Division of Endocrinology, Metabolism, and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois;
4. Department of Epidemiology, Johns Hopkins University, Baltimore, Maryland;
5. Department of Medicine, University of Vermont, Burlington, Vermont.