The 'blood group O problem' in kidney transplantation--time to change?

BACKGROUND: Patients with blood group O have disadvantages in the allocation of deceased donor organs in the Eurotransplant Kidney Allocation System and fewer ABO-compatible living donors. In order to investigate the consequences of this dilemma, we analysed the outcome of patients with blood group O in our transplantation programme.
METHODS: A single-centre analysis of 1186 waitlisted patients for first deceased donor kidney transplantations between 1996 and 2008 was performed, and the mechanisms of blood group-dependent differences for graft and recipient outcome were assessed.
RESULTS: Median follow-up time until death or end of observation for all waitlisted patients was 66 months (range, 0-158 months) and for 589 recipients of a kidney graft was 61 months (range, 0-158 months). Patients with blood group O had significantly longer waiting times for deceased donor kidney grafts, compared to non-group O recipients (median waiting time, 85 vs 59 months). As a consequence, blood group O patients had an increased risk for death without transplantation (13.1% for O patients vs 9.6% for non-O patients; P < 0.05). Despite a good human leukocyte antigen match, graft outcome tended to be worse in O recipients; 14.1% (95% CI, 8.2-19.9%) of all O kidneys from deceased donors were transplanted into non-O recipients, leading to the accumulation of O recipients on the waiting list.
CONCLUSIONS: The export of blood group O donor kidneys to other blood groups leads to longer waiting times, to a higher death rate and to accumulation of blood group O patients on the waiting list, which will further aggravate the problem in the future. Our results should prompt further research on the issues associated with blood group O. Current allocation systems and living donor kidney exchange programmes should be re-evaluated to address this problem.