1. Departments of Medicine, Obstetrics & Gynecology, and Epidemiology, University of Michigan, Ann Arbor, Michigan
2. Department of Medicine, University of Illinois, Chicago, Illinois
3. Department of Medicine, University of Washington, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
4. Biostatistics Center, George Washington University, Rockville, Maryland
5. Department of Epidemiology & Biostatistics, George Washington University, Washington, DC
6. Department of Medicine, University of California, Los Angeles, California
7. Department of Medicine, Columbia University College of Physicians and Surgeons, New York City, New York
8. Department of Medicine, Johns Hopkins University, Baltimore, Maryland