1. Pediatric Urodynamic Centre; First Affiliated Hospital of Zhengzhou University; Zhengzhou P.R. China
2. Department of Epidemiology and Preventive Medicine; School of Public Health, Monash University; Melbourne Australia
3. Department of Paediatrics; Aarhus University Hospital; Aarhus N Denmark
4. Institute of Clinical Medicine; University of Aarhus; Aarhus N Denmark