Association of the Initial Implementation of Continuous Distribution Allocation Policy with Outcomes for Lung Transplant Candidates by Blood Type.

On 3/9/2023, allocation of donor lungs in the US changed to continuous distribution(CD). Initial implementation of policy was flawed due to a programming error affecting priority of candidates by blood type. While this issue was identified and addressed, the impact of initial policy implementation on blood type O candidates has not been rigorously evaluated. We used SRTR data to evaluate candidate(n=4,738) and recipient(n=4,437) outcomes following CD policy. Using cumulative incidence plots accounting for competing risks and multivariable Cox models, incidence of transplantation pre-policy was similar by blood type (8-month incidence 81.0% vs. 80.5% for blood types-A,B,AB and blood type-O respectively,p=0.57). Following CD policy, blood type-O candidates had lower incidence of transplantation relative to other blood types (8-month incidences 86.3% vs 92.1% respectively,p<0.001) with a significantly lower adjusted hazard ratio(AHR) for transplantation (AHR=0.67,95% C.I. 0.54-0.82). Blood type-O candidates were more likely Hispanic and 'Other' race and had higher rates of waitlist removal or death following CD (6.0% vs 2.9%,p=0.003). Among transplants performed prior to CD, 48% were blood type-O recipients compared to 40% post-CD, representing 138 fewer blood type-O transplants than expected. Type-O blood candidates had significant decline in prognosis relative to other blood groups following initial implementation of CD policy.