The impact of bariatric surgery (BS) on kidney transplantation (KT) outcomes in patients with obesity remains controversial. We systematically searched MEDLINE, EMBASE, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials for studies reporting outcomes of KT recipients that underwent prior BS. Common/random effects meta-analyses were performed to obtain summary ratios of the postoperative outcomes. Eighteen eligible studies involving 315 patients were identified. Sleeve gastrectomy was the most common BS type (65.7%) followed by Roux-en-Y gastric bypass (27.6%) and gastric banding (4.4%). Across studies that provided the data, the %excess weight loss from BS to KT was 62.79% (95% confidence interval [CI], 52.01-73.56; range, 46.2%-80.3%). The rates of delayed graft function and acute rejection were 16% (95% CI, 7%-28%) and 16% (95% CI, 11%-23%) in 14 and 11 studies that provided this data, respectively. The rates of wound, urinary, and vascular complications following KT were 5% (95% CI, 0%-13%),19% (95% CI, 2%-42%), and 2% (95% CI, 0%-5%), in 12, 9, and 11 studies that provided this data, respectively. Follow-up time after KT was reported in 11 studies (61.1%) and ranged from 16 mo to >5 y. Graft loss was reported in 14 studies with an average of 3% (95% CI, 1%-6%). Four studies that included a comparator group of patients with obesity who did not undergo BS before KT showed comparable outcomes between the groups. We conclude that currently there is a paucity of robust evidence to suggest that pretransplant BS has a major effect on post-KT outcomes. High-quality studies are needed to fully evaluate the impact of BS on KT outcomes.
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