First Kidney Allograft Mismatch and Survival in American Indians

Abstract

Over 121,000 individuals are awaiting renal allograft in the United States.1 This ongoing imbalance of supply and demand has made research aiming to improve renal allograft survival a necessity. Details of the collection, distribution, and outcomes of renal allografts found in the United Network for Organ Sharing (UNOS) database were used in a retrospective study to identify and evaluate differences in allograft survival between American Indians and other heritage groups. In particular, the study aimed to identify whether American Indians have a similar distribution of HLA mismatches between recipient and donor when compared to other populations; and whether this impacts overall kidney allograft survival. Contingency table and Cox Regression analyses were applied and found that the Hazard Ratio was greater than 1 for all mismatches; and furthermore, an increase in mismatches was proportional to an increase in hazard ratio that was statistically significant. Recipients with 4, 5, or 6 mismatches showed a hazard ratio of 1.466 (p<0.0564). The HLA-DR allele has been known historically as the most important locus for transplants.2 Better matching, particularly at the DR locus, results in improved kidney survival time. Additionally, age, gender, and transplant era were used as major covariates in allograft survival using a proportional hazards model. Increasing age of recipient is associated with increased kidney survival time, and female gender is associated with decreased kidney survival time. Transplant era had a very high Chi-Square of 40.22 and an overall 5% increased survival with most recent transplants living longer than older era transplants. These results have implications for potential policy changes regarding organ allocation in addition to identifying an increased need in organ donation within specific heritage groups.