Why Canadians with cystic fibrosis live 10 years longer than patients in U.S.
Over the last two decades there’s been a big improvement in survival rates for people with cystic fibrosis, with patients in Canada living 10 years longer than those in the U.S.
People with cystic fibrosis are living to a median age of 50.9 years in Canada, compared with 40.6 years in the U.S., according to research published in the Annals of Internal Medicine.
And that’s years longer than the life expectancy 25 years ago, when Erick Braun was first diagnosed with the disease.
“I was diagnosed when I was five years old,” Braun told CBC News, as he awaited treatment at St. Michael’s Hospital in Toronto, which has the largest adult cystic fibrosis clinic in Canada.
“At the time, the life expectancy for people with cystic fibrosis was about 17 years of age, so certainly now, being 31 years old, I’ve come a long way, but still see many good years left in my future hopefully.”
Differences between Canada and U.S.
About 4,100 people in Canada have cystic fibrosis, compared with 30,000 in the U.S.
Researchers, including Dr. Anne Stephenson, a respirologist and cystic fibrosis researcher at St. Michael’s Hospital, identified three factors that seemed to account for the difference in survival rates between the two countries:
- Number of lung transplants.
- Health insurance status.
Stephenson said researchers first noted a difference in survival rates in reports from the Canadian CF Registry and the U.S. Cystic Fibrosis 35 Foundation (CFF) Patient Registry.
“When we realized there was a difference in survival rates between the two countries, we realized this is an opportunity to identify reasons for that gap, so we can then implement strategies to close the gap,” she said.
To eliminate the possibility that different techniques in processing data might change the results, researchers used a standard approach to study data from the five years 1999 to 2013. It showed Americans with cystic fibrosis lived to a median age of 40.6 years, compared with 50.9 years for Canadians.
The study found a greater proportion of patients in Canada had transplants (of any organ) — 10.3 per cent of patients vs. 6.5 per cent.
“There are not many therapies that impact survival immediately, and lung transplant is one of those therapies,” Stephenson said.
‘In Canada … although the survival is very good, there are people who die every year at an early age of CF, so we can’t sit back on our laurels, we have to move survival forward.’ – Dr. Anne Stephenson, St. Michael’s Hospital in Toronto
Unlike Canada, the U.S. uses a “lung allocation score” to determine who gets priority for transplants. The scoring system looks at potential improvement and survival after a transplant, said Dr. Bruce Marshall, senior vice-president for clinical affairs at the CF Foundation in the U.S., who was one of the investigators on the study.
“The impact that it’s had is that it seems to be disadvantaging CF patients a little bit,” he said. “The Canadians have stayed with the same allocation system and it’s the front-line clinician that really knows the patients and helps prioritize who should get donor lungs when they become available.”
High fat diet seems beneficial
A spike in Canadian survival rates noted in 1995 may be due to a high fat diet, emphasizing cheeses, fish and nuts, recommended for Canadians with cystic fibrosis since the 1970s.
One of the organs that can be damaged by the disease is the pancreas, affecting how well nutrition is absorbed by the body, said Marshall.
“The Canadians tried high fat diets, more calories, more palatable, and this really had an impact on the nutritional status, particularly with children, and that seems to set the trajectory for the disease,” he said.
The U.S. began adopting the high fat diet for cystic fibrosis patients in the 1980s, so its survival rates are still catching up.
But the biggest difference may be in the health-care systems of the two countries and equitable access to treatment.
“People who had private insurance in the U.S. had a similar risk of death compared to Canadians … whereas people in Canada had a 77 per cent lower risk of death compared with people in the U.S. with no insurance,” Stephenson said.
People in the U.S. relying on Medicaid and Medicare also had a higher risk of death than Canadians.
Socioeconomic status may also affect care for Canadian cystic fibrosis patients, especially if they do not live close to a clinic where the disease can be treated or cannot afford to take time off work for intensive therapies, Stephenson said.
Researchers say more study is needed to confirm why there is such a difference in survival rates between two countries, and to take into account factors such as air quality, differences in medication usage and in pulmonary function.
The goal is a fuller, longer life for those with cystic fibrosis.
The disease causes the body to produce a thick, sticky mucus that clogs the lungs and leads to life-threatening lung infections. One of the most common causes of death is progressive lung disease, but there also can be complications from the drugs taken for treatment and from other infections.
Struggle to manage disease
Braun described spending five weeks in hospital over Christmas with an infection. He also must take 60 pills a day, along with more than two hours of therapy, to manage the disease.
“One of the biggest challenges is that as CF patients get older and, certainly I’ve experienced this over the years, living with the disease becomes more complex,” Braun said.
He’s holding out hope for a cure within his lifetime.
Stephenson agreed there’s still much to be learned about CF.
“In Canada … although the survival is very good, there are people who die every year at an early age of CF, so we can’t sit back on our laurels, we have to move survival forward.”