Effects of Blood Group and ABO Compatibility on Lung Transplant Waitlist and Post-Transplant Outcomes

Abstract

PurposeBlood group O individuals are universal donors, but O recipients are limited to O donors. This constraint combined with the current lung allocation system places O recipients at a hypothetical disadvantage. This study evaluates waitlist outcomes, post-transplant outcomes, and overall survival from time of listing by blood group.MethodsLung transplant candidates from 2/2015 - 2/2019 were identified from the Scientific Registry of Transplant Recipients. A Fine and Gray model adjusted for OPO region, height, sex, and LAS was used to determine the competing risk for waitlist mortality or transplant by blood group and a model adjusted for LAS at transplant used to determine the competing risk for post-transplant mortality. A Cox proportional hazards regression model utilizing a time-varying covariate of transplant and adjusted for the above was used to determine the adjusted risk from listing to death by blood group. Unadjusted outcomes were visualized using Kaplan-Meir curves.ResultsA total of 9,846 candidates were identified, with 8,181 (83%) receiving a lung transplant and 964 (10%) experiencing waitlist death. Blood group A candidates had higher adjusted access to transplant (sHR 1.23, 1.17-1.29) and lower waitlist mortality (sHR 0.77, CI 0.66-0.89) (Fig 1a). AB candidates had a higher adjusted access to transplant (sHR 1.24, CI 1.1-1.4). There was no difference in the adjusted risk for post-transplant death by blood type (Fig 1b). There was no significant difference in mortality from time of listing across blood groups (Fig 1c) and in graft failure or post-transplant mortality by ABO compatibility.ConclusionTransplant equity varies across blood groups with significant differences in adjusted access to transplant and waitlist mortality by blood group. Despite this, post-transplant survival and survival from the time of listing are similar across blood groups. These results support the need to reconsider allocation schemas to mitigate blood group waitlist inequalities. Blood group O individuals are universal donors, but O recipients are limited to O donors. This constraint combined with the current lung allocation system places O recipients at a hypothetical disadvantage. This study evaluates waitlist outcomes, post-transplant outcomes, and overall survival from time of listing by blood group. Lung transplant candidates from 2/2015 - 2/2019 were identified from the Scientific Registry of Transplant Recipients. A Fine and Gray model adjusted for OPO region, height, sex, and LAS was used to determine the competing risk for waitlist mortality or transplant by blood group and a model adjusted for LAS at transplant used to determine the competing risk for post-transplant mortality. A Cox proportional hazards regression model utilizing a time-varying covariate of transplant and adjusted for the above was used to determine the adjusted risk from listing to death by blood group. Unadjusted outcomes were visualized using Kaplan-Meir curves. A total of 9,846 candidates were identified, with 8,181 (83%) receiving a lung transplant and 964 (10%) experiencing waitlist death. Blood group A candidates had higher adjusted access to transplant (sHR 1.23, 1.17-1.29) and lower waitlist mortality (sHR 0.77, CI 0.66-0.89) (Fig 1a). AB candidates had a higher adjusted access to transplant (sHR 1.24, CI 1.1-1.4). There was no difference in the adjusted risk for post-transplant death by blood type (Fig 1b). There was no significant difference in mortality from time of listing across blood groups (Fig 1c) and in graft failure or post-transplant mortality by ABO compatibility. Transplant equity varies across blood groups with significant differences in adjusted access to transplant and waitlist mortality by blood group. Despite this, post-transplant survival and survival from the time of listing are similar across blood groups. These results support the need to reconsider allocation schemas to mitigate blood group waitlist inequalities.