A New Risk Stratification Score for Deceased Donor Kidneys in Korea

Abstract

Organ shortages have led to expansions in the criteria for deceased donors. Although the expanded criteria donor (ECD)/standard criteria donor (SCD) dichotomous criteria have been useful for making decisions about accepting organ offers, several studies reported that these criteria are too simple to predict prognosis sufficiently. The Kidney Donor Risk Index (KDRI) is based on 10 donor factors, therefore providing a finely granulated evaluation of donor kidney quality. Kidney Donor Profile Index (KDPI) that was derived from KDRI, was newly adopted as an alternative to ECD/SCD in the US. However, the KDPI based on US data may not have similar prognostic values in other countries. Here, we developed a Korean risk stratification score for deceased donor kidney using data obtained from the KONOS (Korean Network for Organ Sharing) and KOTRY (Korean Organ Transplantation RegistrY), and investigated its prognostic values. We analyzed 5,524 first-time, deceased donor adult kidney transplants between 2000 and 2016. A Cox regression model was used to find out independent risk factors among donor and transplant-related factors for graft failure, adjusted for recipient characteristics. There were 426 deaths and 483 graft loss during median follow-up of 49 months. The mean age of donors were 44 years old, and 32% of donor were females. Nine hundred seventeen donors had history of hypertension, and the cause of death was cerebrovascular event in 2,597 donors. Fifty-three donated organ after cardiac death, and mean cold ischemic time was 322 minutes. Twenty-three percent belonged to ECD. Median KDRI was 1.18 and KDPI was 67. A New Korean Kidney Donor Risk Index (K-KDRI) includes 6 donor and transplant factors, each found to be independently associated with graft failure: donor age, weight, history of diabetes, serum creatinine, cerebrovascular cause of death, and HLA mismatch. Median K- KDRI was 1.5. A New Korean Kidney Donor Profile Index (K-KDPI) is a remapping of the K-KDRI onto a cumulative percentage scale. The lowest K-KDPI group (<20%) showed better graft survival than the higher K-KDPI groups (20-80%, ≥80%, respectively) (p<0.001). Even within the ECD group, higher K-KDPI values were significantly associated with lower graft survival rate. In contrast, in the same K-KDPI group, there was no difference in graft survival rate between ECD and SCD. These data suggested that K-KDPI is a better prognostic tool for graft outcomes than the previous ECD/SCD criteria. The new K-KDPI criteria based on the Korean data are expected to give better information about graft prognosis and assist decision making for deceased donor kidney utilization in Korea. KONOS (Korean Network for Organ Sharing). KOTRY (Korean Organ Transplantation Registry).