1. Dow Division of Health Services Research, Department of Urology, University of Michigan Medical School, Ann Arbor, Michigan
2. Litholink Corporation, Laboratory Corporation of America Holdings, Itasca, Illinois
3. Department of Urology, Vanderbilt University Medical Center, Nashville, Tennessee
4. Department of Urology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama
5. Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan