Survival does not differ by annual center transplant volume—A Pediatric Heart Transplant Society Registry study

Background: There are conflicting data regarding the relationship between center volume and outcomes in pediatric heart transplantation. Previous studies have not fully accounted for differences in case mix, particularly in high-risk congenital heart disease (CHD) groups. We aimed to evaluate the relationship between center volume and outcomes using the Pediatric Heart Transplant Society (PHTS) Registry and explore how case mix may affect outcomes. Methods: A retrospective cohort study of all pediatric patients in the PHTS Registry who received a heart transplant from 2009 to 2018 was performed. Centers were divided into 5 groups based on average yearly transplant volume. The primary outcome was time to death or graft loss and outcomes were compared using Kaplan–Meier analysis. Results: There were 4583 cases among 55 centers included. There was no difference in time to death or graft loss by center volume in the entire cohort (p =.75), in patients with CHD (p =.79) or in patients with cardiomyopathy (p =.23). There was also no difference in time to death or graft loss by center size in patients undergoing transplant after Norwood, Glenn or Fontan (log rank p =.17, p =.31, and p =.10 respectively). There was a statistically significant difference in outcomes by center size in the positive crossmatch group (p <.0001), though no discernible pattern related to high or low center volume. Conclusions: Outcomes are similar among transplant centers of all sizes, including for high-risk patient groups with CHD. Future work is needed to understand how patient-specific risk factors may vary among centers of various sizes and whether this influences patient outcomes.