1. Department of Urology, University of California, San Francisco, San Francisco, California.
2. Division of Urology, Faculty of Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Chulalongkorn University, Bangkok, Thailand.
3. Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California.
4. Department of Urology, Tsinghua Changgung Hospital, Beijing, China.