A Time-to-Equivalent Risk (TiTER) for decision-making in deceased donor kidney transplant candidates

A United States study proposed the concept of Time-to-Equivalent Risk (TiTER) as a decision-making tool for accepting organs from expanded-criteria donors. While this study demonstrated a higher initial cumulative incidence of deceased donor kidney transplantation (DDKT) than death, the applicability and pattern of TiTER may differ in regions with extreme organ scarcity, such as Korea.

Using comprehensive, nationwide cohort data from the Korean Network for Organ Sharing registry and National Health Insurance (2008-2022), we analyzed the cumulative incidence and competing risks of DDKT versus waitlist mortality, estimating the Korean TiTER (K-TiTER). Analyses were stratified by recipient age, Korean Estimated Post-Transplant Survival (K-EPTS), blood type, and donor quality.

Among 51,427 waitlisted patients, 10,603 (20.6%) received DDKT. The cumulative incidence of DDKT was initially lower than that of death, in the opposite pattern to the United States study. Therefore, K-TiTER was defined as the earliest time when DDKT probability exceeds waitlist mortality. Among candidates aged ≥65 years, those with high K-EPTS scores (75-100), or blood type O, K-TiTER was frequently not reached, as the waitlist mortality consistently exceeded transplant probability. Notably, sensitivity analyses showed that expanding donor acceptance criteria shortened the time to probability crossover. This finding reframes suboptimal donor organs as a strategic accelerator for mitigating waitlist mortality, especially in candidates with poor prognosis.

This descriptive study proposed preliminary hypotheses for the K-TiTER framework, indicating its potential to guide the identification of vulnerable candidates and support tailored allocation strategies or enrollment in innovative clinical trials for high-risk candidates.