1. Clinical Epidemiology Unit Qilu Hospital of Shandong University Jinan China
2. Department of Gastroenterology Qilu HospitalCheeloo College of MedicineShandong University Jinan China
3. Clinical Research Center of Shandong University Qilu HospitalCheeloo College of MedicineShandong University Jinan China
4. Department of Epidemiology and Health Statistics School of Public Health Cheeloo College of MedicineShandong University Jinan China