© 2006 American Thoracic Society
Not So Fast—Don't Deprive Children with Cystic Fibrosis of the Option for Lung TransplantationTo the Editor:Liou and colleagues deserve commendation for developing outcome models for cystic fibrosis (CF), particularly their report integrating data from two large databases to provide guidance for timing lung transplantation in CF (1). However, we dispute their statement: "Our results may suggest a rigid cutoff age of 18 for lung transplantation." Before using the conclusion "Transplantation never improves the survivorship for pediatric patients" to support changing allocation policy to exclude children with CF from lung transplantation, one must be certain of the accuracy of the underlying models. For several reasons, Liou's model may overestimate pretransplant survival of pediatric candidates. The CF survivorship models do not include supplemental oxygen requirement or ventilator use. These significant predictors of waiting list mortality are included in the current lung allocation system (2). Nor does the model include PCO2. Without measures of gas exchange, we doubt that the CF survivorship model accurately predicts mortality. Also, patients listed for transplant are less likely to have current data in the CF Foundation Patient Registry (CFFPR). Because CFFPR data are used to benchmark CF centers, those patients with current data may have only their best results entered. The CF survivorship model has not been validated independently for either of the critical populations—children or transplant candidates. Moreover, the CF survivorship model cohort specifically excluded transplant recipients, removing patients who might otherwise have died (3). Liou and coworkers also assume that their post-transplant survival model, derived from patients receiving transplants between 1991 and 2001, accurately predicts current expected survival. They do not address how modeling the improved survival they observed in recently transplanted patients might have affected their conclusion. Because the survival curves presented for children nearly overlap, small changes resulting from the above concerns might alter the conclusion. The article also lacks a comparison to the previously reported lung transplant survival benefit for children with CF (4), which used a similar analysis, but perhaps a more appropriate control population comprised of CF patients awaiting transplant. Finally, we hope that future similar articles containing recommendations for changes in organ allocation will be accompanied by an editorial representing the views of those responsible for developing transplant policy. We commend the AJRCCM for publishing this article, which will undoubtedly generate provocative discussion about the appropriate timing for lung transplantation in CF. Nonetheless, we feel strongly that until models like these can accurately predict outcomes for an individual, they should never be used to exclude any population of patients from access to transplant.
St.Louis Children's Hospital at Washington University, St.Louis, Missouri FOOTNOTES Conflict of Interest Statement: Neither of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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