Impact of weight change on kidney transplantation outcomes: A systematic review and meta-analysis

Background and Aim: Kidney transplant recipients frequently experience a wide range of metabolic complications, including weight changes, which significantly impact patient outcomes and graft function, yet the relationship between weight gain and transplant outcomes remains poorly understood. This systematic review and meta-analysis aimed to synthesise existing evidence on the influence of weight gain on patient and graft outcomes following kidney transplantation to enhance clinical practice and optimise post-transplant care strategies. Materials and Methods: A literature search was conducted across databases such as PubMed and Scopus for peer-reviewed studies published up to 8 August 2024. We included adult kidney transplant recipients (ages 18 years and older) with substantial and clinically relevant post-transplant weight gain and a control group without such changes, focusing on outcomes including all-cause mortality, graft survival, cardiovascular events and acute rejection. Results: The pooled analysis, which included data from 11 studies, indicated no significant association between post-transplant weight gain and the risk of all-cause mortality (hazard ratio [HR] 1.21, 95% confidence interval [CI] 0.69 to 2.10, p = 0.51; I-2 = 28%), cardiovascular events (HR 0.93, 95% CI 0.43 to 2.01, p = 0.85; I-2 = 32%) or acute rejection (HR 1.13, 95% CI 0.76 to 1.68, p = 0.55; I-2 = 9%). However, weight gain was significantly associated with an increased risk of graft failure (HR 1.58, 95% CI 1.22 to 2.05, p < 0.001; I-2 = 0%). Conclusion: Substantial and clinically relevant weight gain after kidney transplant was associated with a higher risk of graft failure. Within the timeframes of study observation, risks of all-cause mortality, cardiovascular events or acute rejection were not increased by weight gain in kidney transplant recipients.