C. Holscher1, K. Jackson1, A. Thomas1, C. Purcell2, M. Ronin2, A. Massie1, J. Garonzik Wang1, D. Segev1 1Johns Hopkins University,Baltimore, MD, USA 2National Kidney Registry,New York, NY, USA
Introduction: In order to utilize a willing but incompatible living donor, transplant candidates must either proceed with incompatible living donor kidney transplantation or attempt to find a more compatible match using kidney paired donation (KPD). For the latter, the benefit of a “better” match must be balanced with the morbidity and mortality associated with increased dialysis time while searching for a match. A common criticism of KPD registries is that the "easy-to-match" candidates match and leave the registry pool quickly, and thereby create a registry pool concentrated with difficult to match patients, making future KPD matches challenging. We hypothesized that, given alternative treatments such as deceased donor kidney transplant priority and desensitization, this concern would no longer be the case.
Methods: We studied 1894 registrants to the National Kidney Registry (NKR), the largest KPD registry in the United States (US), between 2011 and 2015. Candidates were considered a part of the KPD registry pool for the year they registered, and remained in the pool after registration until they matched into a KPD transplant or were removed from the registry for other reasons such as death, receipt of a deceased donor kidney transplant, or incompatible living donor transplant. The prevalent composition of the NKR pool was compared across years, comparing by age, gender, race/ethnicity, body mass index (BMI), ABO blood type, and panel reactive antibody (PRA) categories. Comparisons were made with chi-square, ANOVA, and t-tests, as appropriate.
Results: Candidates were median age 50 (IQR: 38-60) years, 48% female, 66% white, and had a median BMI of 27 (23-31). Overall, 59% of candidates had blood type O, 24% had blood type A, 15% had blood type B, and 2% had blood type AB. The mean PRA was 53 with 29% having a PRA of 0, 29% having a PRA of 1-79, 18% having a PRA 80-97, and 24% having a PRA 98 or higher. Notably, there were no statistically significant differences by year in age, gender, race, BMI, blood type, or PRA. Further, there were no statistically significant changes by year in the composition of the pool by PRA category (Figure).
Conclusion: In the largest KPD registry in the US, there is no evidence that KPD registrants have become more difficult to match over time. This should encourage continued enrollment of incompatible donor/recipient pairs in KPD registries to facilitate compatible transplantation.
