1. Department of Epidemiology, School of Public Health, Zhengzhou University, Zhengzhou, Henan, China
2. Department of Urology, Zhengzhou Third People's Hospital, Zhengzhou, Henan, China
3. Department of General Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
4. Department of International Medicine, Beaumont Health System, Royal Oak, MI, USA