Korean OBEsity Surgical Treatment Study (KOBESS): Protocol of a prospective multicentre cohort study on obese patients undergoing laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass

Introduction Bariatric surgery effectively induces long-term weight loss in Western populations. However, its effectiveness in Asians remains to be confirmed objectively. The Korean Society for Metabolic and Bariatric Surgery proposes the first prospective cohort study on Koreans undergoing bariatric surgery. Methods and analysis The Korean OBEsity Surgical treatment Study (KOBESS) is a prospective, multicentre, single-arm, observational, cohort study on morbidly obese patients who undergo primary sleeve gastrectomy or Roux-en-Y gastric bypass in Korea. In total, 100 consecutive obese Asian patients who will undergo bariatric surgery will be recruited in 2016-2017; follow-up will be for 1 year. Primary outcomes are change in body weight and waist circumference at 1 year. All patients will undergo anthropometry, laboratory tests, bioelectrical impedance analysis, gastrofibroscopy, polysomnography and fat-measuring CT before and after surgery. Patients with diabetes will also undergo perioperative oral glucose tolerance and endocrinological hormone tests. Hypertensive patients will also undergo perioperative echocardiography and carotid Doppler ultrasonography. Female patients suspected of having polycystic ovarian syndrome will also undergo perioperative hormone tests and abdominal ultrasonography. Visceral and subcutaneous fat will be harvested during surgery. Blood, stool and urine samples will be taken at various perioperative time points. Although the cohort is small and the follow-up duration is relatively short, this study will determine whether bariatric surgery induces satisfactory weight loss in obese Koreans. Significantly, the tissue samples will also facilitate many studies examining the effects of bariatric surgery and their mechanisms. Ethics and dissemination Ethics approval was obtained from the institutional review board of each participating hospital. All findings arising from this cohort study will be published in open-access peer-reviewed journals and will be presented at national and international meetings. All KOBESS investigators will be able to propose research studies and potential publications based on KOBESS data and tissue samples. Trial registration number NCT03100292; Pre-results.