Survival Benefit Tradeoff: When a Lower KDPI Kidney Does Not Outweigh the Risks of Waiting

BACKGROUND: Decisions to accept or refuse kidney organ offers require transplant programs and patients to evaluate a multifaceted set of risk factors. The risks of accumulating more dialysis time on the waitlist must be weighed against offer features including the Kidney Donor Profile Index (KDPI). METHODS: In this analysis, we use a modern period-prevalent cohort of adult nonpreemptive kidney-alone candidates and recipients from the Scientific Registry of Transplant Recipients. We fit Cox proportional hazards models with time-varying coefficients modeled flexibly with splines to characterize the risks of increasing dialysis exposure on the waitlist and posttransplant mortality. We also incorporate time-varying coefficients for KDPI at allocation to characterize the benefits associated with higher-quality offers. We develop a novel measure to characterize the tradeoff between the benefits of a lower KDPI offer and the risks of waiting on dialysis for it. RESULTS: A key result is a tradeoff heat map showing the number of months on dialysis that would offset the survival benefit of waiting for a lower KDPI kidney, across values of KDPI, age, and patient diagnosis. CONCLUSIONS: For nonpreemptive candidates, each extra month on dialysis diminishes the potential gains of waiting for a lower KDPI offer-although the extent of this effect depends on patient characteristics and the timing of the offer.