Cystic Fibrosis Survival in US Lags 10 Years Behind Canada, Researchers Find

March 14, 2017

A concerning new study has found a significant gap in survival for cystic fibrosis patients in the United States and Canada. The 10-year advantage observed in Canadian patients could partially be explained by disparities in the countries’ healthcare systems, the researchers suggested.

A concerning new study has found a significant gap in survival for cystic fibrosis patients in the United States and Canada. The 10-year advantage observed in Canadian patients could partially be explained by disparities in the countries’ healthcare systems, the researchers suggested.

According to national disease registries, the median survival age for patients with cystic fibrosis in 2011 was 36.8 years in the US and 48.5 years in Canada. However, direct comparison of these statistics may be misleading due to differences in data collection and analysis between the 2 countries’ registries. To provide a more accurate view of the potential gap in survival outcomes, researchers used a standardized approach to calculate the differences in survival between Canada and the US. Their findings were published in the Annals of Internal Medicine.

The cohort study analyzed data collected from 1990 through 2013 from 42 cystic fibrosis care centers in Canada and 110 in the US. Besides the main outcome of median survival age, the researchers also recorded data on the patients’ transplant status, sex, race, clinical genotype, insurance status, and other variables, along with their cause of death and age at death when applicable. Overall, the databases tracked 45,448 American and 5941 Canadian patients with cystic fibrosis; death rates throughout the study period were 21.2% and 21.7%, respectively.

These similar death rates belie some concerning trends in age of survival within the 2 countries. While median survival age increased during the study period in both nations, the rate of improvement was significantly greater in Canada, beginning in 1995 and becoming even more pronounced in 2005. The median survival age in Canada was 50.9 years, over 10 years greater than that in the US at 40.6 years. Furthermore, American patients who died had a shorter lifespan, as their median age at death was 26.9 years, compared with 31.9 years for their Canadian counterparts.

After adjusting the statistical analysis for patient characteristics, the risk of death in Canada was 41% lower than in the US. Even when incorporating clinical factors, the patients in Canada had a 34% lower mortality risk. The researchers also compared the risk of death for US patients with different types of insurance with the death risk of patients in Canada, who are covered under a single-payer universal healthcare system. The Canadian patients had a death risk 44% lower than that of the US patients continuously receiving Medicaid or Medicare, and a 77% lower mortality risk than the Americans with unknown or no health insurance.

According to the researchers, this survival gap “raise[s] the question of whether a disparity exists in access to therapeutic approaches or health care delivery such that hypotheses may be generated for further investigation.” They referenced prior research on the importance of lung transplantation that had found Canadian recipients of lung transplants had a longer median survival time than comparable American patients.

However, the study authors acknowledged that the different healthcare delivery systems are another likely driver of the survival gap in cystic fibrosis. They noted that the risk of death among Americans with insurance other than Medicaid or Medicare (ie, generally private coverage) was similar to that of the Canadians in the study.

An accompanying editorial in the same issue zeroed in on this factor as the most likely culprit of the disparities in survival and mortality. The authors reasoned that differences in lung transplant procedures or nutritional guidelines, while associated with increased risk, were not expected to result in the 10-year survival advantage observed among Canadians. Instead, they wrote, the survival gap “seems to be based on fundamental differences in the 2 nations’ health care systems,” as their delivery infrastructures “have markedly dissimilar effects on disadvantaged patients.”