1. Division of Pediatric Urology, Children's Medical Center Dallas and Department of Urology, University of Texas, Southwestern, Dallas, Texas
2. Department of Urology, University of Washington School of Medicine, Seattle, Washington
3. Department of Epidemiology, University of Washington School of Medicine, Seattle, Washington
4. Department of Surgery, University of Toronto, Toronto, Ontario, Canada
5. Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington