1. Division of Urology, Seattle Children's Hospital, University of Washington, Seattle, WA, United States
2. Division of Urology, Hospital Universitario San Ignacio, Pontificia Universidad Javeriana, Bogotá, Colombia
3. Division of Urology, Children's Hospital of Philadelphia, Philadelphia, PA, United States
4. Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States