Changes in Kidney Allocation System and Effect on Kidney Transplantation in Elderly Transplant Recipients

Background: The aging US population and rising rates of diabetes have led to more elderly patients needing kidney transplants. These patients face higher mortality and lower graft survival. In response, the Kidney Allocation System (KAS) was revised, with major updates in 2021 (KAS250), aiming to improve access and equity. This study evaluates the impact of these changes, amid the COVID-19 pandemic, on patient and graft survival in elderly recipients. Methods: This retrospective analysis included all primary deceased donor kidney transplants for patients aged 65 and older from January 1, 2010, to December 31, 2023. The study periods were categorized into three eras: pre-KAS (2010-2014), KAS (2015-2020), and KAS250 (2021-2024). Descriptive statistics, Kaplan-Meier survival analysis, and Cox regression models were used to compare outcomes across these periods, with adjustments for demographic and clinical risk factors. A separate analysis was performed to account for COVID-19-related mortality Results: A total of 39,630 elderly patients received kidney transplants during the study period. The number of transplants increased significantly with the introduction of KAS and KAS250, with a notable rise in preemptive transplants. The proportion of patients over 69 years old at the time of transplant and those with increased comorbidities, such as diabetes and peripheral vascular disease, also grew significantly over time (p<.0001). Patient survival decreased slightly between the preKAS and KAS250 eras, with a 1-year survival rate of 93.7% in pre-KAS, 93.5% in KAS, and 92.8% in KAS250 (P<.0001). Graft survival remained high, with 1-year graft survival rates of 90.5%, 91.0%, and 89.9%, respectively. After adjusting for COVID-19-related deaths, the short-term survival rates were similar between the 3 periods. Multivariable analysis showed an increased risk of death and graft failure associated with older age, male gender, diabetes, and longer dialysis time, with the risk of graft failure worsening in the KAS250 era. Conclusion: KAS reforms increased transplant access for elderly patients, particularly preemptively. While patient survival declined slightly, graft survival stayed robust. Despite greater use of marginal donors, graft outcomes were stable, underscoring the need for continued evaluation of policy impacts, especially amid COVID-19.