Safety and Effectiveness of Metabolic and Bariatric Surgery Before and After Kidney Transplantation: A Systematic Review and Meta-Analysis.

BACKGROUND

Kidney transplantation is the optimal treatment for end-stage kidney disease. However, obesity limits access to and success of this procedure. While metabolic and bariatric surgery (MBS) can address obesity, its safety and effectiveness in transplant candidates and recipients have not been fully elucidated.

METHODS

This systematic review and meta-analysis aimed to evaluate the safety and effectiveness of MBS performed in relation to kidney transplantation. Six databases were searched up to February 2, 2026. Randomized clinical trials and observational studies from any geographic region investigating MBS in adult kidney transplant candidates or recipients were included.

RESULTS

A total of 49 studies (1504 patients) were included. For pre-transplant surgery (1215 patients), the pooled observed waitlisting rate was 78.0% (95% CI 66.0-88.0%; I²=90.3%; based on 26 studies comprising 719 patients), the observed transplantation rate was 52.0% (95% CI 36.0-68.0%; I²=96.3%; based on 32 studies comprising 1249 patients), and the 1-year graft survival rate was > 99% (95% CI 98%-100%; I²=17.5%; based on 11 studies comprising 232 patients). For post-transplant surgery (289 patients), the diabetes improvement rate was 93% (95% CI 64-100%; I²=21.4%; based on 4 studies comprising 52 patients) and the hypertension improvement rate was 92% (95% CI 54-100%; I²=52.7%; based on 3 studies comprising 38 patients) (defined as medication reduction/cessation or improvement in HbA1c/blood pressure). Waitlisting rates varied significantly by country (P < 0.001) but not by procedure type (P = 0.09). Formal tests did not detect small-study effects where assessable, but power was limited and selective outcome reporting remains possible. High heterogeneity limits generalizability.

CONCLUSION

In selected patients with severe obesity, pre-transplant MBS was associated with transplantation access, and post-transplant surgery with metabolic improvement in small cohorts. Observed complication rates were acceptable, but controlled studies are needed. Because the evidence is predominantly observational and heterogeneous, comparative safety and long-term graft effects remain uncertain.