Weight Loss, Comorbidity, and Complications After Single-anastomosis Sleeve Ileal Bypass (SASI): A Systematic Review and Meta-analysis

Single anastomosis sleeve ileal (SASI) bypass combines sleeve gastrectomy with intestinal bipartition to promote weight loss and metabolic improvement. We conducted a systematic review and meta-analysis comparing SASI with sleeve gastrectomy (1 RCT and 4 non-randomized comparative studies (NRCTs)), one-anastomosis gastric bypass (2 RCTs, 4 NRCTs), and Roux-en-Y gastric bypass (2 NRCTs), regarding weight loss, metabolic and nutritional outcomes, and adverse effects. Certainty of evidence was assessed with GRADE for 1-year outcomes. Twenty-six studies (1603 patients) were included, mostly reporting 12-month results. Pooled single-arm analysis from 11 studies showed mean total weight loss of 35.9 kg (95% CI 33.3–38.5). The certainty of evidence ranged from low to very low, limiting confidence in the results and emphasizing the need for high-quality RCTs. We are very uncertain whether SASI differs from SG, OAGB, or RYGB for weight loss at 12 months (very low-certainty evidence). SASI may result in better outcomes for diabetes remission compared to SG (low-certainty evidence), but we are very uncertain about comparisons with OAGB and RYGB (very low-certainty evidence). The evidence base consists of few, small studies with substantial methodological limitations, and data beyond 12 months are scarce. High-quality, adequately powered RCTs with standardized techniques and longer follow-up are needed to establish the comparative effectiveness of SASI.