1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, School of MedicineKyungpook National UniversityDaegu Republic of Korea
2. Center of Biostatistics, School of MedicineKyungpook National UniversityDaegu Republic of Korea
3. Department of Occupational and Environmental MedicineDongguk University Gyeongju HospitalGyeongju Republic of Korea