Efficiency and safety of single anastomosis sleeve ileal (SASI) bypass in the treatment of obesity and associated comorbidities: a systematic review and meta-analysis

The Single Anastomosis Sleeve Ileal (SASI) bypass is a new bariatric surgery corresponding to an adaptation of the Santoro approach, consisting of a sleeve gastrectomy (SG) followed by loop gastroileostomy. Therefore, we aimed to systematically assess all the current literature on SASI bypass in terms of safety, weight loss, improvement in associated comorbidities, and complications.

Following the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) recommendations, we conducted a systematic review and meta-analysis by searching three databases (PubMed, Scopus, and Web of Science). We performed a meta-analysis of risk ratios and mean differences to compare surgical approaches for excessive weight loss, improvement/remission in type 2 diabetes mellitus (T2DM), hypertension (HT), dyslipidemia (DL), obstructive sleep apnea (OSA), and complications. Heterogeneity was assessed using the I² statistic.

Eighteen studies were included in the qualitative analysis and four in the quantitative analysis, comparing SASI bypass with SG and One-Anastomosis Gastric Bypass (OAGB). A comparison between Roux-en-Y Gastric Bypass (RYGB) and SASI bypass could not be performed. Compared to SG, the SASI bypass was associated with improved weight loss (MD = 11.32; 95% confidence interval (95%CI) [7.89;14.76]; p < 0.0001), and improvement or remission in T2DM (RR = 1.35; 95%CI [1.07;1.69]; p = 0.011), DL (RR = 1.41; 95%CI [1.00;1.99]; p = 0.048) and OSA (RR = 1.50; 95%CI [1.01;2.22]; p = 0.042). No statistically significant differences in any of the assessed outcomes were observed when compared with OAGB. When compared to both SG and OAGB, the complication rate of SASI was similar.

Although studies with longer follow-up periods are needed, this systematic review and meta-analysis showed that SASI bypass has a significant effect on weight loss and metabolic variables. Variations in outcomes between studies reinforce the need for standardization.