Safety and Efficacy of Single- and Two-step Metabolic and Bariatric Surgery in the Setting of Obesity with ≥ 50 kg/m2 BMI: A Network Meta-analysis

The surgical management of patients with obesity and body mass index (BMI) ≥ 50 kg/m² remains challenging, with no clear consensus on the optimal approach. Single-step and two-step metabolic and bariatric surgeries (MBS) are both used, but their comparative efficacy and safety have not been fully elucidated. This research aims to compare the outcomes of single-step and two-step MBS in patients with obesity and BMI ≥ 50 kg/m². A systematic review and network meta-analysis including 56 studies was conducted following the PRISMA guidelines and the Cochrane protocol searching PubMed, Scopus, Embase, Web of Science, and Cochrane library up to the 28th of February 2025. Primary outcomes included percentage excess weight loss (%EWL) at 1-, 3-, and 5-years follow-up, while secondary outcomes included postoperative mortality, morbidity, and resolution of obesity-related medical problems. Data were synthesized using a NMA framework, integrating both direct and indirect comparisons. At 1 year, SADI, RYGB, and BPD achieved the highest %EWL, while LAGB and IGB were least effective. At 3 years, BPD ranked best, whereas IGB remained consistently inferior. At 5 years, BPD maintained superiority, followed by OAGB. For postoperative mortality, OAGB and LSG were associated with the lowest risk, whereas BPD and IGB combinations performed worst. Regarding morbidity, OAGB and LAGB had the most favorable safety profile, while BPD showed the highest complication rates. For comorbidity resolution, BPD was the most effective for T2D, AH, and OSAS. Overall, restrictive procedures offered better short-term safety, while malabsorptive techniques provided superior long-term metabolic outcomes. MBS offer effective weight loss and metabolic improvements in individuals with BMI ≥ 50 kg/m². Two-step procedures may provide metabolic advantages in higher BMI populations, while single-step surgeries offer lower surgical risk and acceptable efficacy. Future randomized studies with standardized outcome definitions are necessary to optimize surgical decision-making in this complex patient group.