1. Department of Biometry and Epidemiology, Medical University of South Carolina Charleston, South Carolina, 29425–2503
2. Department of Medicine, Division of Cardiology, Medical University of South Carolina, Charleston, South Carolina, 29425
3. Evans County, Georgia, Heart Study, Claxton, Georgia, 30417
4. Department of Epidemiology, University of North Carolina, Chapel Hill, North Carolina, 27599