Canadians with cystic fibrosis tend to survive longer than American patients – a lot longer, a new study has found.

According to research published Monday in Annals of Internal Medicine, Canadian CF patients live more than 10 years longer on average than patients with the same disease in the U.S.

The study looking at CF patients from 1990 to 2013 found the median age of survival for Canadian patients is now 50.9 years. But the median life expectancy in the U.S. is still stuck at 40.6 years.

Cystic fibrosis is an incurable genetic disease that causes the buildup of mucus in the lungs, pancreas and intestines. In the lungs, the mucus clogs airways, leading to lung damage, infections and eventually respiratory failure.

Not that long ago, a child with CF rarely lived long enough to finish elementary school. But thanks to improvements in drug treatments, better nutrition and newer medications, life expectancy in both countries has grown considerably.

But in recent years, doctors have noticed that patients in Canada tend to live quite a bit longer, reports study author Dr. Anne Stephenson, a respirologist and scientist at St. Michael’s Hospital in Toronto.

“We noticed a few years ago that the statistics that we had in Canada seemed to differ from the ones that were published in the U.S.,” she told CTV News.

“That made us stop and think we should look at this in a more formal way. We should do a systematic approach to this analysis and see if this difference is really there.”

So they looked over cystic fibrosis registry data for 5,941 patients in Canada and 45,456 patients in the U.S., from 1990 to 2013 and noticed the 10-year survival gap.

Even after adjusting for the ages and disease severity of the patients they studied, the risk for death among CF patients was 34 per cent lower in Canada than in the United States.

Although the study didn’t seek to explain the gap, Dr. Stephenson says there are a number of factors that may have played a part.

For one, Canadian doctors began recommending nutritional supplementation to CF patients 10 years earlier than in the U.S.

In the 1970s, Canadians with cystic fibrosis were told to adopt a high-calorie, high-fat diet and to take pancreatic enzyme supplements and vitamin supplements at every meal. These supplements help patients get the nutrients their disease prevents them from absorbing, to help them maintain a healthy weight and avoid infections.

U.S. patients eventually adopted these nutritional changes but not until the 1980s.

For many years, a higher proportion of Canadian cystic fibrosis patients also received lung transplants than those in the U.S.

But one of the key differences between the two countries is that Canadians have universal, publicly funded health care while Americans do not.

In the study group, Canadian CF patients as a whole had a 77 per cent lower risk for death than U.S. patients with no health insurance or who health insurance status was unknown. They also had a 44 per cent lower death risk than Americans receiving continuous Medicaid or Medicare, and a 36 per cent lower risk than those receiving intermittent Medicaid or Medicare coverage.

“We need to look further into why there is such a dramatic gap between the two countries because that’s a really important thing for CF patients not only in the U.S. but all over the world,” Dr. Stephenson said.

CF patient Shannon Price says she feels fortunate to be almost 42 years old and still doing well, especially considering her parents were told when she was born in 1975 that she would not likely see the age of 12.

“I think for myself, I feel a lot of gratitude to be living in Canada and having access to our health-care system,” she said. “And I have private insurance as well and that has played major roles in my success story and why I am still here.”

Price said she has lots of friends with CF who live in the United States and she wants “everyone in the world who has CF to have the same fighting chance.”

Dr. Stephenson says that while it is good that Canadian CF patients have a higher median life expectancy than they did a few decades ago, it is still lower than the average person. And CF remains an onerous and exhausting disease for patients for which there is no cure, she notes.

But she hopes that this study highlighting the different factors in U.S. and Canadian survival will be the first step in making changes.

“I think this research highlights the importance of these factors so we can improve survival for all Canadians and all Americans and other people around the world who are living with this disease,” she said.

Dr. Bruce Marshall of the U.S. Cystic Fibrosis Foundation agreed that the study helped doctors gain some important insights about what helps patients, although more research needs to be done.

“We’ve made substantial progress in both the U.S. and Canada, but 40 years of age or 50 years of age is not enough,” he said. “To even to get to 40 or 50, that’s with a very heavy treatment burden, so there’s a lot of research that needs to be done to advance to a normal life expectancy so these people can live, long, productive and healthy lives.”

With a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip