1. Second Hospital of Lanzhou University; Department of Urology; No. 82, Cui Ying Men Street Lanzhou City Gansu China 730030
2. London School of Hygiene & Tropical Medicine; Department of Non-Communicable Disease Epidemiology; Keppel Street London UK WC1E 7HT
3. Second Hospital of Lanzhou University; Institute of Urology; No. 82, Cui Ying Men Street Lanzhou City Gansu China 730030
4. Lanzhou University; Evidence-Based Medicine Center, School of Basic Medical Sciences; No. 199, Donggang West Road Lanzhou City Gansu China 730000