People with cystic fibrosis (CF) survive an average of 10 years longer if they live in Canada than if they live in the United States, according to a report published online March 14 in Annals of Internal Medicine.
Differences between the two nations’ health care systems, including access to insurance, “may, in part, explain the Canadian survival advantage,” said Anne L. Stephenson, MD, PhD, of St. Michael’s Hospital, Toronto, and her associates.
Previous studies have suggested a significant survival gap between Americans and Canadians with CF, but their conclusions were “problematic” because of inherent differences between the two countries in registry data, which complicated direct comparisons. Dr. Stephenson and her associates used several statistical strategies to adjust for these differences, and confirmed the discrepancy in survival by analyzing information for 45,448 U.S. patients and 5,941 Canadian patients treated at 110 U.S. and 42 Canadian specialty centers from 1990 through 2013.
Overall there were 9,654 U.S. deaths and 1,288 Canadian deaths during the study period, for nearly identical overall mortality between the two countries (21.2% and 21.7%, respectively). However, the median survival was 10 years longer in Canada (50.9 years) than in the United States (40.6 years), a gap that persisted across numerous analyses that adjusted for patient characteristics and clinical factors, including CF severity.
One particular difference between the two study populations was found to be key: Canada has single-payer universal health insurance, while the United States does not. When U.S. patients were categorized according to their insurance status, Canadians had a 44% lower risk of death than did U.S. patients receiving continuous Medicaid or Medicare (95% confidence interval, 0.45-0.71; P less than .001), a 36% lower risk than for U.S. patients receiving intermittent Medicaid or Medicare (95% CI, 0.51-0.80; P = .002), and a 77% lower risk of death than U.S. patients with no or unknown health insurance (95% CI, 0.14-0.37; P less than .001), the investigators said (Ann. Intern. Med. 2017 Mar 14. doi: 10.7326/M16-0858). In contrast, there was no survival advantage for Canadian patients when compared with U.S. patients who had private health insurance. This “[raises] the question of whether a disparity exists in access to therapeutic approaches or health care delivery,” the researchers noted.
This study was supported by the U.S. Cystic Fibrosis Foundation, Cystic Fibrosis Canada, the National Institutes of Health, and the U.S. Food and Drug Administration. Dr. Stephenson reported grants from the Cystic Fibrosis Foundation and fees from Cystic Fibrosis Canada. Several of the study’s other authors reported receiving fees from various sources and one of those authors reported serving on the boards of pharmaceutical companies.