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Multicenter collaboration in pediatric lung transplantation – The importance of consensus

The recent article on lung transplantation for patients with lung disease related to bone marrow transplant (1) is an important example of a successful multicenter collaborative effort to overcome the chronic challenge faced by pediatric transplantation – small volume. Indeed, for pediatric lung transplantation, where only 125 transplants are performed in the world each year, volume is a significant challenge. Roughly 40 centers have reported pediatric lung transplants during each of the past few years (yielding an average of 2–3 transplants per center per year). However, almost half of the transplants are performed in the six most active centers. Thus, nearly 90% of centers reporting pediatric lung transplants perform 1– 4 transplants per year (2). So, it is clear that learning from the pediatric lung transplant clinical experience requires collaboration, and the International Pediatric Lung Transplant Collaborative (IPLTC) has been successful in that regard, at least in terms of retrospective studies (3–8). The study by Yousef compared outcomes in 11 patients from six of the 25 IPLTC centers who received lung transplantation at a time point 18–123 months after bone marrow transplantation (BMT) for respiratory complications, primarily related to chronic graft-versus-host disease. The transplants occurred during a 15-yr period beginning in 1995. For the majority of that time window, the immunosuppression and induction protocols varied by center. The post-lung transplant outcomes of these patients were compared with a cohort of patients with cystic fibrosis (CF) who received their transplant at one active center during the latter half of the above period. Controls were matched by age, gender, and immunosuppression protocol. The authors noted that the control (CF) population had a higher median FEV1 but also a higher requirement for supplemental oxygen at transplant than the BMT cases. The BMT group had a longer median post-transplant hospital stay than the control group (28 vs. 11 days). There were more deaths in the first-yr post-transplant in the BMT group although the overall survival was comparable between groups. The frequency of acute rejection was lower in the BMT group compared with the control group (no episodes were seen in the BMT group). In contrast the rate of CMV infection was higher in the BMT group (36% vs. 11%). Lung function at one-yr post-transplant was comparable between groups. The authors concluded that lung transplantation should be a consideration in children with end-stage lung disease related to chronic graft-versus-host disease following bone marrow transplantation. They also suggest that careful monitoring of immune reconstitution and infection be performed to balance the risks of infection and rejection in a population which may, by virtue of the BMT, be more immunosuppressed than children with CF and other diseases who receive lung transplant. This study exposes many of the limitations of the multicenter retrospective approach. Only 25% of the centers who are members of the IPLTC contributed patients to the study, limiting the potential power to detect differences in outcome and raising the question whether the reported outcomes are reflective of the entire pediatric experience. Although more complete survival data may be available from the ISHLT registry, disease specific outcomes are not provided in the ISHLT registry annual report. Regardless, the registry dataset is limited in terms of the level of post-transplant detail related to infection and rejection. So, the registry would likely not have been able to provide sufficient