Impact of extended criteria donor transplants on infections in kidney and liver transplant recipients and marginal donor definition criteria: a systematic review

Background Expanded criteria donors (ECDs) have become an important source of organs, but their association with infection risk remains unclear. This systematic review assessed the impact of ECD versus standard criteria donors (SCD) on infection rates in kidney and liver transplant recipients and analysed the variability of ECD definitions. Methods Three different literature databases were searched up to June 2024 for randomized controlled trials or observational studies comparing infection rates between ECD and SCD recipients. Studies without quantitative data or comparator groups were excluded. Outcomes were measured at 30-180 days and 1-3-5 years post-transplant, evaluating both bacterial and viral infections. Results A total of 11,119 articles were screened and 131 studies included. At 30 days, bacterial infections occurred at similar rates between ECD and SCD recipients (OR 1.15, 95% CI 0.86-1.53, p=0.36). However, liver transplant recipients from ECDs had a higher infection risk (OR 1.73, 95% CI 1.12-2.68, p=0.01). Definitions of ECD varied notably, especially in liver transplantation, while kidney transplantation criteria were more consistent. Conclusions Current evidence does not definitively establish a link between ECD and infection risk, highlighting the need for standardized donor definitions and routine reporting of infections as ECD outcomes.