Survival Comparison of Patients With Cystic Fibrosis in Canada and the United States

Abstract

Background In 2011, the median age of survival in cystic fibrosis (CF) reported in the United States (US) was 36.8 years compared to 48.5 years in Canada; however direct comparison of survival estimates between national registries is challenging because of inherent differences in methodologies used, data processing techniques, and ascertainment bias. Objectives To use a standardized approach to calculate CF survival estimates and to explore differences between Canada and the United States (US). Design Population-based study. Setting 42 Canadian CF clinics and 110 CF care centers in the US. Patients Patients followed in the Canadian CF Registry (CCFR) and the US Cystic Fibrosis Foundation (CFF) Patient Registry (CFFPR) between 1990 and 2013. Measurement Cox proportional hazards models were used to compare survival between patients followed in the CCFR (n=5,941) and CFFPR (n=45,448). Multivariable models were used to adjust for factors known to be associated with survival. Results Median age of survival in patients with CF increased in both countries between 1990 and 2013; however in 1995 and 2005, survival in Canada increased at a faster rate relative to the US (p<0.001). Using contemporary data from 2009-2013, the median age of survival in Canada was ten years greater than the US (50.9 vs. 40.6 years, respectively). The adjusted risk of death was 34% lower in Canada compared to the US (hazard ratio 0.66, 95% CI 0.54-0.81). A greater proportion of patients had transplants in Canada (10.3% vs. 6.5% respectively, SD 13.7). Differences in survival between US and Canadian patients varied according to the US patients' insurance status. Limitations Ascertainment bias as a result of missing data or non-random lost to follow-up could impact the results. Conclusions Differences in CF survival between Canada and the US persisted after adjusting for risk factors associated with survival. Differential access to transplantation, improved post-transplant survival and differences in the healthcare systems may, in part, explain the Canadian survival advantage.

Reference percentiles of FEV1 for the Canadian cystic fibrosis population: comparisons across time and countries

“…Those with lower lung function are at higher risk of death, and therefore, the fact that Canadians have higher level of lung function in the lower percentiles is consistent with better overall survival in Canada compared with the USA 24. The high fat diet was implemented earlier in Canada compared with the USA which may explain the higher level of lung function in Canadians with CF 24. These cross-population differences highlight the necessity for CF-specific reference equations that are population specific.…”

“…Furthermore, the data showed a wider gap in those with lower lung function compared with those at higher percentiles. Those with lower lung function are at higher risk of death, and therefore, the fact that Canadians have higher level of lung function in the lower percentiles is consistent with better overall survival in Canada compared with the USA 24. The high fat diet was implemented earlier in Canada compared with the USA which may explain the higher level of lung function in Canadians with CF 24.…”

Precision Medicine In Action: The Impact Of Ivacaftor On Cystic Fibrosis–Related Hospitalizations

“…7 Prior evidence suggests that people with the disease on Medicaid experience worse health outcomes, compared to those with private insurance. 23 We repeated our analysis with a Medicaid sample and found smaller reductions in inpatient admissions (38 percent for all-cause and 46 percent for cystic fibrosis–related admissions), compared to the reductions experienced by the privately insured. (See appendix exhibit A3 for our analysis of the Medicaid sample.)…”

Innovating cystic fibrosis clinical trial designs in an era of successful standard of care therapies

“…As the formulary of therapies approved for cystic fibrosis (CF) has expanded since the approval of the first therapy in 1993 [1], these treatments have become standards of care and have contributed towards substantial improvements in morbidity and mortality for individuals with CF across the decades [2]. Clinical investigators exploring newer or alternative versions of these established therapies have been forced away from traditional additive study designs, in which study subjects are randomly allocated to receive either a novel active treatment or a placebo, towards studies which employ active comparators consisting of these current ‘standards of care’.…”