1 Department of Gastroenterology, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, Zhejiang, PR China.
2 Department of Gastroenterology, Jining First People's Hospital, Jining, Shangdong, PR China.
3 Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Naval Medical University, Shanghai, PR China.
4 Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Naval Medical University, Shanghai, PR China. Electronic address: wanglei@smmu.edu.cn.