March 15, 2017

In Canada, those with cystic fibrosis live a decade longer than in the US

Daily Briefing

Cystic fibrosis patients in Canada on average live a decade longer than cystic fibrosis patients in the United States, according to a study published Monday in the Annals of Internal Medicine.

Cystic fibrosis is a life-threatening genetic disorder that attacks the lungs and digestive system.

Methodology

For the study, researchers looked at data on about 6,000 patients in the Canadian Cystic Fibrosis Registry and about 45,000 patients in the U.S. Cystic Fibrosis Patient Registry between 1990 and 2013. To estimate median expected survival, the researchers looked at a five-year period that ended in 2013.

The U.S. Cystic Fibrosis Foundation funded the study.

Canadian patients outlive US counterparts

When looking at both patients who lived and died during the five-year study period, the researchers found that median life expectancy was 50.9 years for Canadian patients with cystic Fibrosis, compared with 40.6 for those in the United States.

When looking only at the patients who passed away during the study period, the researchers found that the median age of death was 31.9 for Canadians, versus 26.9 for Americans. The researchers said that Canadians over the five-year period had a 34 percent lower risk of dying than the Americans.

Lead study author Anne Stephenson, a researcher at the University of Toronto and the Adult Cystic Fibrosis Center at St. Michael's Hospital in Toronto, said the disparity in survival rates persisted when researchers accounted for differences in the severity of patients' cases.

The researchers added that while both countries have seen improvements in cystic fibrosis survival rates, the life expectancy for cystic fibrosis patients since the late 1990s has increased faster in Canada than in the United States. According to the researchers, that survival gap widened considerably starting in 2005, likely as a result of changes in how the United States prioritizes cystic fibrosis patients for transplant waiting lists.

Understanding the disparity

The study "was not designed to investigate the underlying reasons that contributed to the gap" between the countries and more research is needed to examine those factors, according to a spokesperson for the Cystic Fibrosis Foundation. However, the researchers hypothesized several different factors that could play a role in the disparity, such as differences in how Canada and the United States approach health insurance.

According to Stephenson, the researchers found that patients in the United States with private health insurance had similar survival rates to patients in Canada—which has a universal health care system. However, when the researchers compared survival rates between Canadian patients and U.S. patients who had public coverage or were uninsured, the researchers found that Canadian patients had a:

  • 44 percent lower risk of death than U.S. patients who had continuous Medicare or Medicaid coverage; and
  • 77 percent lower risk of death than U.S. patients who were uninsured or whose insurance status was not known.

Gregory Sawicki, director of the Cystic Fibrosis Center at Boston Children's Hospital, said one of the biggest challenges, in terms of access to care for U.S. Medicaid patients, is patients' access to medication. According to Sawicki, cystic fibrosis patients may have to take 10 to 15 drugs daily—and some of those medications may not be covered by Medicaid.

However, Christopher Gross, a co-author on the study, said Medicaid often provides less costly and more comprehensive coverage for cystic fibrosis patients than private insurance. According to Gross, that suggests that the Medicaid and Medicare patients likely fared worse because of other factors related to low income, such as having less help from family members to get to doctors' appointments and difficulty affording the high-caloric diet necessary to help patients maintain their weight. As Stephenson put it, "It's difficult to separate the access to care and your socioeconomic status."

Another factor that could influence the disparity, according to the researchers, is the difference in how the two countries implement new treatment regimens. For instance, Canada in the 1970s adopted a high-fat diet associated with better survival in cystic fibrosis patients—a diet regimen that the United States didn't adopt until 1980s.

A third possible factor influencing the disparity could be differences in how Canada and the United States select patients for lung transplants, the researchers said. According to the researchers, cystic fibrosis patients in Canada are more likely than those in the United States to receive a lung transplant.

Discussion

Kevin Gorey, a University of Windsor epidemiologist who studies how health outcomes differ on each side of the border, called the disparity "stunning" and said it is probably the biggest survival difference he has ever seen. "A 10-year difference … that's lots of years spent with your child or not, having fun with your friends, living your life," Gorey said. "That's a huge, huge human tragedy."

Stephenson said "people should be alarmed" by the findings. "It will make people motivated to reduce that gap," she explained.

Patrick Flume—a researcher at the Medical University of South Carolina, who wrote an accompanying editorial to the study—told Reuters, "I think that the overall survival differences between Canada and the United States, and the large survival gap especially in cystic fibrosis patients, is an outcome that demonstrates how the market based approach is less successful" (Boodman, STAT News, 3/13; Walker, Wall Street Journal, 3/13; Rappaport, Reuters, 3/13; Stephenson et al., Annals of Internal Medicine, 3/14).

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