Waiting list mortality among children listed for heart transplantation in the United States

Abstract

Background: Children listed for heart transplantation face the highest waiting list mortality in solid-organ transplantation medicine. We examined waiting list mortality since the pediatric heart allocation system was revised in 1999 to determine whether the revised allocation system is prioritizing patients optimally and to identify specific high-risk populations that may benefit from emerging pediatric cardiac assist devices.

Methods and results: We conducted a multicenter cohort study using the US Scientific Registry of Transplant Recipients. All children <18 years of age who were listed for a heart transplant between 1999 and 2006 were included. Among 3098 children, the median age was 2 years (interquartile range 0.3 to 12 years), and median weight was 12.3 kg (interquartile range 5 to 38 kg); 1294 (42%) were nonwhite; and 1874 (60%) were listed as status 1A (of whom 30% were ventilated and 18% were on extracorporeal membrane oxygenation). Overall, 533 (17%) died, 1943 (63%) received transplants, and 252 (8%) recovered; 370 (12%) remained listed. Multivariate predictors of waiting list mortality include extracorporeal membrane oxygenation support (hazard ratio [HR] 3.1, 95% confidence interval [CI] 2.4 to 3.9), ventilator support (HR 1.9, 95% CI 1.6 to 2.4), listing status 1A (HR 2.2, 95% CI 1.7 to 2.7), congenital heart disease (HR 2.2, 95% CI 1.8 to 2.6), dialysis support (HR 1.9, 95% CI 1.2 to 3.0), and nonwhite race/ethnicity (HR 1.7, 95% CI 1.4 to 2.0).

Conclusions: US waiting list mortality for pediatric heart transplantation remains unacceptably high in the current era. Specific high-risk subgroups can be identified that may benefit from emerging pediatric cardiac assist technologies. The current pediatric heart-allocation system captures medical urgency poorly. Further research is needed to define the optimal organ-allocation system for pediatric heart transplantation.

Figure 1

Kaplan-Meier survival for all children listed for heart transplant according to listing status (A) and for those children listed as status 1A according to invasive hemodynamic support(B).

Figure 2

Competing outcomes for wait-listed children according to UNOS status at the time of listing (A, B, and C), and for children listed as status 1A according to their level of invasive hemodynamic support: ECMO (D), mechanical ventilation (E), and neither ECMO nor mechanical ventilation (F).

Figure 2

Competing outcomes for wait-listed children according to UNOS status at the time of listing (A, B, and C), and for children listed as status 1A according to their level of invasive hemodynamic support: ECMO (D), mechanical ventilation (E), and neither ECMO nor mechanical ventilation (F).

Figure 2

Competing outcomes for wait-listed children according to UNOS status at the time of listing (A, B, and C), and for children listed as status 1A according to their level of invasive hemodynamic support: ECMO (D), mechanical ventilation (E), and neither ECMO nor mechanical ventilation (F).

Figure 3

Number of children who died while on the waiting list according to weight at listing (n=533). The numbers above each bar denote the total number of children who were listed for heart transplant within each weight category.