[1] North Sichuan Med Coll, Inst Basic Med & Forens Med, Nanchong 637000, Sichuan, Peoples R China
[2] North Sichuan Med Coll, Affiliated Hosp, Dept Gastroenterol, Nanchong 637000, Sichuan, Peoples R China
[3] Huazhong Univ Sci & Technol, Union Hosp, Tongji Med Coll, Dept Gastrointestinal Surg, Wuhan 430022, Hubei, Peoples R China
[4] North Sichuan Med Coll, Inst Basic Med & Forens Med, 55 Dongshun Rd, Nanchong 637000, Sichuan, Peoples R China