Age- and sex-specific effects on weight loss outcomes in a comparison of sleeve gastrectomy and Roux-en-Y gastric bypass: a retrospective cohort study

BACKGROUND Roux-en-Y gastric bypass (RYGBP) and sleeve gastrectomy (SG) are the most common bariatric procedures undertaken globally but there are no evidenced-based criteria that inform the selection of one operation over the other. The purpose of this study was thus to compare weight loss outcomes between RYGBP and SG, and to define patient factors affecting weight loss. METHODS A single-centre two-year follow-up retrospective cohort study of all adults who underwent either RYGBP (n = 422) or SG (n = 432) between 2007 and 2012, at University College London Hospitals National Health Service Foundation Trust, an academic tertiary referral centre, was undertaken. Multilevel linear regression was used to compare weight loss between groups, enabling adjustment for preoperative BMI (body mass index) and evaluation for interaction factors. RESULTS One- and two-year results showed that unadjusted BMI loss was similar between groups; 13.7 kg/m(2) (95% CI: 12.9, 14.6 kg/m(2)) and 12.8 kg/m(2) (95% CI: 11.8, 13.9 kg/m(2)) for RYGBP patients respectively compared with 13.3 kg/m(2) (95% CI: 12.0, 14.6 kg/m(2)) and 11.5 kg/m(2) (95% CI: 10.1, 13.0 kg/m(2)) for SG patients respectively. Adjusting for preoperative BMI, there was 2.2 kg/m(2) (95% CI: 1.5, 2.8) and 2.3 kg/m(2) (95% CI: 1.3, 3.3) greater BMI loss in the RYGBP group compared to the SG group at one and two years respectively (P < 0.001 for both). The interaction analyses demonstrated that age and sex had important differential impacts on SG and RYGBP weight outcomes. Men under 40 and women over 50 years obtained on average far less benefit from SG compared to RYGBP, whereas men over 40 years and women under 50 years experienced similar weight loss with either procedure (P = 0.001 and 0.022 for interaction effects at one and two years respectively). CONCLUSIONS Our results show that patient sex and age significantly impact on weight loss in a procedure-dependent manner and should be considered when choosing between RYGBP and SG. Optimizing procedure selection could enhance the effectiveness of bariatric surgery, thus further increasing the benefit-to-risk ratio of this highly effective intervention.