Pediatric Lung Allocation: The Rest of the Story
http://onlinelibrary.wiley.com/doi/10.1111/ajt.12546/fullEditorial
S. C. Sweet1,*, M. L. Barr2
DOI: 10.1111/ajt.12546
American Journal of Transplantation
Early View (Online Version of Record published before inclusion in an issue)
In their article “The Equitable Allocation of Deceased Donor Lungs for Transplant in Children in the United States,” Snyder et al [1] provide an objective analysis of the waiting list mortality and transplant rate for children under 12 years of age before and after the implementation of the US lung allocation system. The primary conclusion from their article is that there is no significant difference between either metric for pediatric lung transplant candidates in the 6- to 11-year-old age group compared to older children and adults. Although the authors acknowledge the fact that children under 12 continue to receive organs based on waiting time creates significantly different listing practices in comparison to older candidates (likely underestimating waiting list mortality for children under 12), the tacit implication is that the widely publicized case advanced by the parents of Sarah Murnaghan, the child in Philadelphia, is without merit.
Recognizing the reality that those providing information for the case often oversimplified the data and those passing judgment did so based their decision largely on subjective rather than objective criteria, there are several other aspects of this case that should be considered as the Organ Procurement and Transplantation Network (OPTN) and the transplant community consider whether changes to pediatric lung allocation are warranted.
One of the arguments presented by the family (which resonated with the media) is that there are too few donor lungs for children under 12. The court filing states “the pool of lungs donated from adults is more than 50 times larger than the pool of lungs donated from children” [2]. Unfortunately, this perspective does not take into account the demand side of the equation. Indeed, the pool of adult transplant candidates is more than 50 times larger than the number of pediatric candidates. So the actual number of lungs recovered from donors under 12 reflects both donor availability and candidate demand. In fact, roughly 5% of the 400+ donors each year under 12 provide lungs compared to more than 35% of the 400+ adolescent donors (Figure 1). It is unlikely that donor characteristics are solely responsible for the lower percentage. Thus one area of focus for the pediatric lung transplant community should be to explore tapping into this apparent opportunity.
The second concept propagated by this story is that lobar transplant from adult donors is the best solution to the (perceived) lack of lung donors for children under 12. Although this option may be appropriate for children in circumstances where experienced transplant surgeons and physicians counsel the family that waiting for suitably sized donor organs from a pediatric donor is not feasible, the reality is that there are limited data supporting this approach for young children (in the most widely referenced series, the youngest recipient of an adult deceased donor lobar transplant was 9 years old) [3]. Moreover, the authors' experience with living donor lobar transplant suggests that size matching is critical to successful outcome. Thus, a change to the allocation system that encourages increased use of lobar transplant for young children would be premature.
Other data reviewed by the OPTN Pediatric, Thoracic and Executive Committees influencing the final decision in this case included competing risks analyses demonstrating that, in the first year after listing, a higher percentage of children under 12 died without transplant compared to older children and adults (35% for children 6–11 compared to 11% for adolescents and 12% for adults). In an analysis exploring the effect of the two-tiered priority system implemented in 2010, a higher percentage of children under 12 died within a year of listing after the policy went into effect compared to children listed previously (30% vs. 26% for children 6–11). In addition, analysis of recent lung offer data demonstrated that fewer children under 12 received at least one offer compared to older children and adults (0–5: 53.7% and 6–11: 69.4%, compared to 12–17: 87% and 18+: 93.2%) [4]. Although these analyses involve small numbers and are subject to the same listing practice caveats mentioned above, they still raise questions about how children under 12 fare with the current lung allocation policies. Because of these questions, and because the National Organ Transplant Act directs the OPTN to adopt criteria, policies and procedures that “address the unique health care needs of children” the OPTN Executive committee opted to provide a lung review board appeal mechanism to provide transplant centers who feel adult lobar transplant from a deceased donor would be appropriate for a lung transplant candidate under 12, a lung allocation score for ranking within the older pool of candidates. This policy is consistent with appeal mechanisms for candidates of other solid organs. It will expire in June 2014 unless extended by the OPTN board.
Finally, and perhaps most importantly, one aspect of providing children under 12 increased priority for access to donors 12 and older deserves emphasis. It allows increased access to adolescent organs that may be of suitable size for children nearing age 12 especially from a young adolescent donor. Indeed, in the current environment more than 90% of adolescent donor lungs are being transplanted into adult recipients [5]. As recent work suggests that transplanting undersized lungs carries risk for early and late complications [6, 7], it may be appropriate to consider broader sharing of adolescent organs to ensure that, within constraints imposed by ischemic time limits, lungs from pediatric donors are offered to all pediatric candidates before being offered to adults.
In summary, the available data do not completely allay the concerns raised by the Sarah Murnaghan case. Opportunities for improvement include bringing the lung donor yield in the 0–11 age group closer to the yield in adolescents, relaxing geographic allocation boundaries to ensure that pediatric lungs are offered first to children and reserving deceased donor lobar transplant for circumstances where suitably sized donor organs are not available.
Topic: Equitable Allocation of Deceased Donor Lungs for Transplant in Children in USA (Read 3309 times)