1. Department of Public Health, Section for Epidemiology, Aarhus University, Bartholins Allé 2, Aarhus C, Denmark
2. Department of Epidemiology, Fielding School of Public Health, University of California Los Angeles (UCLA), 650 Charles E. Young Drive South, Los Angeles, CA, USA
3. California Center for Population Research, UCLA, 337 Charles E. Young Drive East, Los Angeles, CA, USA
4. Center for Health Policy Research, UCLA, 337 Charles E. Young Drive East, Los Angeles, CA, USA
5. Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43, Aarhus N, Denmark
6. Department of Urology, Section for Paediatric Urology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 35, Aarhus N, Denmark