Department of Gastroenterology, Xinqiao Hospital of Army Medical University, Chongqing, China. Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Hubei, China. Department of Gastroenterology, Chongqing University Cancer Hospital, Chongqing, China. Department of Gastroenterology, the First Hospital of Lanzhou University, Gansu, China. Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Guizhou, China. Department of Gastroenterology, the Fourth Affiliated Hospital of China Medical University, Liaoning, China. Department of Gastroenterology, the First Affiliated Hospital of Guangxi Medical University, Guangxi, China. Department of Gastroenterology, Fuling Central Hospital, Chongqing, China. Department of Gastroenterology, the Affiliated Hospital of Southwest Medical University, Sichuan, China. Department of Epidemiology, Army Medical University, Chongqing, China. Department of Gastroenterology, Xinqiao Hospital of Army Medical University, Chongqing, China. Electronic address: hguoxqyy@163.com. Department of Gastroenterology, Xinqiao Hospital of Army Medical University, Chongqing, China. Electronic address: Yangshiming@tmmu.edu.cn.