1. Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA
2. Office of Surveillance and Epidemiology, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD
3. Office of Biostatistics, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD
4. Center for Clinical Outcome Research, Kaiser Permanente Georgia, Atlanta, GA
5. Division of Research, Kaiser Permanente Northern California, Oakland, CA