The learning curve of one anastomosis gastric bypass and its impact as a preceding procedure to Roux-en y gastric bypass: Initial experience of one hundred and five consecutive cases

Background: The aim of this study was to assess the learning curve of one anastomosis gastric bypass (OAGB-MGB) at the start of a low volume bariatric unit and analyze its impact as a preceding procedure to Roux-en Y gastric bypass (RYGB). Methods: From January 2014 to December 2017, all patients who underwent bariatric surgeries in our teaching hospital that were performed by the same surgeon were enrolled. The first 47 patients who underwent OAGB-MGB were assigned to group A. RYGB has been offered as a treatment option since July 2016; thereafter, 26 patients who underwent OAGB-MGB and 32 patients who underwent RYGB at the same time interval were assigned to group B and group C, respectively. Baseline characteristics, perioperative outcomes and percentage of total weight loss (%TWL) up to 12 months postoperatively were collected and analyzed between groups. Results: Compared to the patients in group C, those in groups A and B were older (39.4 yrs. and 42.2 yrs., respectively, vs. 34.2 yrs.; p = 0.021) and predominantly male (48.9 and 73.1%, respectively vs. 40.6%; p = 0.04), and they had a higher body mass index (41.8 kg/m² and 43.3 kg/m², respectively vs. 37.7 kg/m²; p = 0.002) and a higher incidence of hypertension (44.7 and 61.5%, respectively vs. 21.9%; p = 0.008). In addition, the operation time was significantly reduced (118.2 min and 115.8 min, respectively vs. 153.1 min; p < 0.001), and the length of stay was shortened (3.0 days and 2.9 days, respectively vs. 3.4 days; p = 0.002) in groups B and C compared to group A. No mortality, conversion or leakage was reported throughout the study period. The 30-day complication rate was decreased in group C compared to groups A and B (0% vs. 6.4 and 7.7%, respectively; p = 0.307). The %TWL at the 12-month follow-up was 36.3, 30.9 and 28.3% for groups A, B and C, respectively (p < 0.001). Conclusion: Our study verified the early emergence of a learning curve effect for OAGB-MGB, and the proficiency acquired can be transferred to subsequent practice for RYGB in terms of acceptable operation time and length of stay without an increase in complications.