Determinants of waiting time for heart transplants in the United States

BACKGROUND: Reports have been published on factors affecting the variations in waiting times for kidney and liver transplant candidates who have been registered on the United Network for Organ Sharing's waiting list. This study reports on determinants of waiting time differences that occur in the eleven UNOS regions for heart transplant candidates. METHODS: Retrospective analysis of 11,345 primary heart waiting-list registrations and 15,868 cadaveric donors, from whom 7,043 hearts were recovered and transplanted for the years 1994-96. Because estimated populations in the eleven UNOS regions vary from 10.8 to 43.2 million, analyses utilized Registrations/million population and Transplants/million population to obtain an R/T ratio. The relationship of the R/T ratio to the median waiting time was then examined for different demographic variables. RESULTS: The numbers of new heart candidate registrations, heart transplants performed, and waiting list deaths have undergone little change from 1991 through 1996. National median waiting times varied by basic demographic variables such as ABO blood type, race, age group, and UNOS medical urgency status. In the eleven UNOS regions, registrations per million ranged from 11.5 to 33.0 and transplants per million from 5.3 to 10.7. Registration/Transplant ratios correlated with median waiting times for urgency Status 1 and 2 as well as for blood group O recipients. Correlation with blood type AB recipients was less consistent, in part, due to the small number of AB recipients. CONCLUSIONS: There are wide variations in the number of heart transplant candidate registrations and in the number of heart transplants performed in the eleven UNOS regions. The registration to transplantation ratio correlated with median waiting times in these regions. Factors possibly contributing to the observed variations were examined.