1. Department of Medicine, American University of Beirut, Beirut, Lebanon
2. Department of Medicine, Boston University School of Medicine, Boston, MA
3. National Heart, Lung, and Blood Institute, Framingham Heart Study, Framingham, MA
4. Department of Medicine, University of Massachusetts Medical School, Worcester, MA;
5. Department of Mathematics and Statistics, Boston University School of Public Health, Boston, MA
6. Department of Epidemiology, Boston University School of Public Health, Boston, MA
7. VA Boston Health Care System, West Roxbury, MA