1. Division of Research, Kaiser Permanente, Northern California Region, Oakland, California;
2. Departments of Epidemiology and Urology, University of Michigan, Ann Arbor, Michigan;
3. The Biostatistics Center, The George Washington University, Rockville, Maryland;
4. National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland;
5. Department of Urology, Northwestern University, Chicago, Illinois;
6. Department of Urology, University of Washington School of Medicine and Harborview Medical Center, Seattle, Washington.