The national impact of the 1995 changes to the UNOS renal allocation system


Mary S. Leffell, Immunogenetics Laboratory, The Johns Hopkins University School of Medicine, 2041 E. Monument St., Baltimore, MD 21205, USA.


In 1995, changes in the United Network for Organ Sharing (UNOS) renal allocation policies expanded the mandatory share (MS) category to include zero antigen mismatches (0 mm), increased points for waiting time and for pediatric status, and eliminated points for certain HLA match grades. Data from the national scientific registry on 11 344 and 11 652 renal allograft recipients were analyzed for periods prior to and following the policy changes to assess the impact on organ allocation. The overall frequency of transplants going to non-Caucasians increased between the study periods, but the increase was significant only in the MS category. The proportion of MS transplants nearly doubled for African-Americans, increasing from 5.5% to 10.5%, while Hispanic/Latino recipients experienced a smaller increase, from 7.2% to 8.9%. The increased numbers of MS transplants clearly resulted from the inclusion of the 0 mm in the MS category. Among the NMS transplants, the average number of mismatched HLA antigens increased slightly. No effect of the additional points for waiting time was observed among recipients of non-mandatory share (NMS) transplants. The increase in mean waiting time until transplant for NMS recipients was attributable to the growth in the size of the waiting list. In contrast, there was a significant increase in mean waiting time for MS recipients. There were no significant changes in the proportions of sensitized or pediatric recipients between the study periods.In conclusion, only the changes in the MS policies appeared to have any significant effect on renal allocation. Further efforts will be required to address increasing allocation to patients disadvantaged by sensitization and/or prolonged waiting times.