A randomized open-label multicentre clinical trial comparing single-anastomosis duodenal switch (SADI-S) versus Roux-en-Y gastric bypass for the treatment of severe obesity: BYPSADIS study protocol.

Abstract

Background: Roux-en-Y gastric bypass (RYGB) is a standard bariatric surgical technique, associated with suboptimal response and recurrent weight gain in 25%-50% of cases. Single-anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S) is a simplification of duodenal switch with promising results. However, a comparison of the two techniques in a randomized clinical trial (RCT) has not yet been reported. This RCT aims to compare SADI-S and RYGB.

Methods: BYPSADIS is a randomized, open-label, multicentre clinical trial comparing SADI-S with RYGB. Patients aged 18-60 years with body mass index (BMI) = 40-50 kg/m² will be recruited in six hospitals. Primary endpoints are as follows: (1) efficacy, measured as percentage of patients with total weight loss (TWL) > 30% at 5 years; and (2) safety, defined as percentage of patients experiencing at least one severe complication either at 90 days postoperatively (Clavien-Dindo >2) or up to 5 years, including severe malnutrition, diarrhea, dumping, hypoglycemia, or need for surgical reintervention. Sample size was calculated for both primary outcomes, needing 432 patients to prove superiority of SADI-S in efficacy and 423 to prove non-inferiority in safety, with statistical power of 0.8, alpha risk of 0.025, assuming 10% loss throughout follow-up. To ensure power for both primary endpoints, 450 subjects will be included, 225 SADI-S and 225 RYGB. Secondary outcomes include metabolic comorbidities, quality of life, digestive symptoms (dumping, bowel habits, and GERD), need of extra supplementations, and alimentary habits. Outcomes will be compared using one-sided 95% confidence interval of proportion difference between groups.

Discussion: To our knowledge, there is only one ongoing RCT comparing SADI-S with RYGB (SADISLEEVE trial, ClinicalTrials.gov identifier NCT03610256), which includes primary and revisional surgeries, without BMI restrictions and with varying limb lengths. The BYPSADIS trial will complement its findings and help to bridge the knowledge gap on whether SADI-S is more effective than RYGB, while offering a similar safety profile.

Trial registration: The study protocol has been approved by the Ethics Committee of the six participating hospitals and has been registered in ClinicalTrials.gov, NCT06789965.