• Anne L Stephenson, Jenna Sykes, Sanja Stanojevic, Bradley S Quon, Bruce C Marshall, Kristofer Petren, Josh Ostrenga, Aliza K Fink, Alexander Elbert, and Christopher H Goss.
• From St. Michael's Hospital, University of Toronto, and The Hospital for Sick Children, Toronto, Ontario, Canada; University of British Columbia, Vancouver, British Columbia, Canada; Cystic Fibrosis Foundation, Bethesda, Maryland; and University of Washington Medical Center, Seattle, Washington.
• Ann. Intern. Med. 2017 Apr 18; 166 (8): 537546537-546.

BackgroundIn 2011, the median age of survival of patients with cystic fibrosis reported in the United States was 36.8 years, compared with 48.5 years in Canada. Direct comparison of survival estimates between national registries is challenging because of inherent differences in methodologies used, data processing techniques, and ascertainment bias.ObjectiveTo use a standardized approach to calculate cystic fibrosis survival estimates and to explore differences between Canada and the United States.DesignPopulation-based study.Setting42 Canadian cystic fibrosis clinics and 110 U.S. cystic fibrosis care centers.PatientsPatients followed in the Canadian Cystic Fibrosis Registry (CCFR) and U.S. Cystic Fibrosis Foundation Patient Registry (CFFPR) between 1990 and 2013.MeasurementsCox proportional hazards models were used to compare survival between patients followed in the CCFR (n = 5941) and those in the CFFPR (n = 45 448). Multivariable models were used to adjust for factors known to be associated with survival.ResultsMedian age of survival in patients with cystic fibrosis increased in both countries between 1990 and 2013; however, in 1995 and 2005, survival in Canada increased at a faster rate than in the United States (P < 0.001). On the basis of contemporary data from 2009 to 2013, the median age of survival in Canada was 10 years greater than in the United States (50.9 vs. 40.6 years, respectively). The adjusted risk for death was 34% lower in Canada than the United States (hazard ratio, 0.66 [95% CI, 0.54 to 0.81]). A greater proportion of patients in Canada received transplants (10.3% vs. 6.5%, respectively [standardized difference, 13.7]). Differences in survival between U.S. and Canadian patients varied according to U.S. patients' insurance status.LimitationAscertainment bias due to missing data or nonrandom loss to follow-up might affect the results.ConclusionDifferences in cystic fibrosis survival between Canada and the United States persisted after adjustment for risk factors associated with survival, except for private-insurance status among U.S. patients. Differential access to transplantation, increased posttransplant survival, and differences in health care systems may, in part, explain the Canadian survival advantage.Primary Funding SourceU.S. Cystic Fibrosis Foundation.

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