(395) - Comparison of Listing Strategies for Allosensitized Heart Transplant Candidates: A Decision Model Analysis

Abstract

Allosensitized children listed with a requirement for a negative prospective/predicted crossmatch (XM) have a high risk of death awaiting heart transplantation (HTx). A strategy of accepting the first suitable organ offer for these patients, regardless of the possibility of a positive XM, should improve waitlist outcomes but it is unclear whether it would result in a net survival benefit (i.e. at all times after listing, including post-transplant). We used decision modeling to compare net survival after listing for 2 competing strategies for allosensitized pediatric HTx candidates: listing with a requirement for a negative prospective XM (wait) vs. acceptance of the first suitable organ offer (take). Model data on waitlist outcomes and post-HTx survival were derived from OPTN data on all status 1A pediatric HTx listings from 1999-2009. We assumed there was no possibility of a positive XM in the "wait" strategy and that the probability of a positive XM in the "take" strategy was equal to the pre-transplant PRA. Model time horizon was 10 yrs from listing. Under base-case assumptions the "take" strategy was favored over the "wait" strategy with an incremental net survival benefit of 1.4 yrs. In sensitivity analyses which varied the probabilities of a positive XM and death after transplantation across a positive XM, the "wait" strategy was favored only when the probability of death after HTx across a positive XM exceeded 13% per yr (equivalent to median post-transplant survival of <5 yrs). The "wait" strategy was never favored when the probability of a positive XM was <65%. Even after adjustment of the model so that waitlist probabilities of death and delisting were equal in both strategies (while maintaining the lower probability of transplantation associated with the "wait" strategy), the "take" strategy was still slightly favored (incremental net benefit 0.3 yrs). Our model predicts that taking the first suitable organ offer, regardless of the potential for a positive XM, results in greater survival at all times after listing (including post-transplant) for allosensitized status 1A pediatric HTx candidates. Presumably this is because the inferior survival after transplantation across a positive XM is more than offset by enhanced waitlist survival. Whether this holds true during very long-term follow-up remains to be determined.