Population Diversity Challenge the External Validity of the European Randomized Controlled Trials Comparing Laparoscopic Gastric Bypass and Sleeve Gastrectomy.

Introduction: Two randomized controlled trials (RCTs) from Europe recently showed similar weight loss and rates of type 2 diabetes (T2D) remission following laparoscopic gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG). However, results from observational studies in the United States (US) have discordant results. We compared 1-year weight loss and T2D remission between LRYGB and LSG in a heterogeneous patient cohort from the US, albeit with similar inclusion and exclusion criteria to the European RCTs.

Methods: Logistic regression was used to propensity match LSG and LRYGB patients according to age, gender, race, preoperative BMI, and T2D. Inclusion and exclusion criteria were adopted from the two European RCTs. Demographic, anthropometric, weight outcomes, and comorbidities prevalence were compared at baseline and 1-year follow-up.

Results: We included 278 patients (139 LSG and 139 RYGB; median age 42 years, 89% female, 57% black race, 22% with public health insurance, and 25% with T2D). One year after surgery, mean %EWL was 77.3 ± 19.5% with LRYGB and 63.1 ± 21% with LSG (P < 0.001). Mean %TWL was 34.2 ± 7.3% after LRYGB and 28.1 ± 8.2% after LSG, (P < 0.001). The proportion of patients who achieved T2D remission was comparable between surgeries (LRGYB: 68.6% vs. LSG: 66.7%, P = 0.89). LSG, older age, black race, and higher preoperative BMI were independently associated with lower %EWL. Independent correlates of weight loss were different for LRYGB and LSG.

Conclusions: Weight loss, but not the likelihood of T2D remission, was greater with LRYGB than LSG in a diverse patient cohort in the US. Further research efforts connecting population diversity to discordant results across studies is needed to better counsel patients with regards to expected postoperative outcomes.