1. Department of Gastroenterology, Kaiser Permanente San Francisco, San Francisco, California
2. Division of Research, Kaiser Permanente Northern California, Oakland, California
3. Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York
4. Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California
5. Department of Family Medicine and Community Health, Perelman School of Medicine, University of Pennsylvania, Philadelphia