Bridging the survival gap in cystic fibrosis: An investigation of lung transplant outcomes in Canada and the United States

Background: Previous literature in cystic fibrosis (CF) has shown a 10-year survival gap between Canada and the United States (US). We hypothesized that differential access to and survival after lung transplantation may contribute to the observed gap. The objectives of this study were to compare CF transplant outcomes between Canada and the US and estimate the potential contribution of transplantation to the survival gap.

Methods: Data from the Canadian CF Registry and the US Cystic Fibrosis Foundation Patient Registry supplemented with data from United Network for Organ Sharing were used. The probability of surviving after transplantation between 2005 and 2016 was calculated using the Kaplan‒Meier method. Survival by insurance status at the time of transplantation and transplant center volume in the US were compared with those in Canada using Cox proportional hazard models. Simulations were used to estimate the contribution of transplantation to the survival gap.

Results: Between 2005 and 2016, there were 2,653 patients in the US and 470 in Canada who underwent lung transplantation for CF. The 1-, 3-, and 5-year survival rates were 88.3%, 71.8%, and 60.3%, respectively, in the US compared with 90.5%, 79.9%, and 69.7%, respectively, in Canada. Patients in the US were also more likely to die on the waitlist (p < 0.01) than patients in Canada. If the proportion of who underwent transplantation and post-transplant survival in the US were to increase to those observed in Canada, we estimate that the survival gap would decrease from 10.8 years to 7.5 years.

Conclusions: Differences in waitlist mortality and post-transplant survival can explain up to a third of the survival gap observed between the US and Canada.