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

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).

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.

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.

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.