The Cystic Fibrosis Survival Rate Dilemma: Canada and the United States

Survival Comparison of Patients With Cystic Fibrosis in Canada and the United States: A Population-Based Cohort Study

Background:In 2011, the median age of survival of patients with cystic fibrosis reported in the United States was 36.8 years, compared with 48.5 years in Canada. Direct comparison of survival estimates between national registries is challenging because of inherent differences in methodologies used, data processing techniques, and ascertainment bias.

Objective:To use a standardized approach to calculate cystic fibrosis survival estimates and to explore differences between Canada and the United States.

Design:Population-based study.

Setting:42 Canadian cystic fibrosis clinics and 110 U.S. cystic fibrosis care centers.

Patients:Patients followed in the Canadian Cystic Fibrosis Registry (CCFR) and U.S. Cystic Fibrosis Foundation Patient Registry (CFFPR) between 1990 and 2013.

Measurements:Cox proportional hazards models were used to compare survival between patients followed in the CCFR (n = 5941) and those in the 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 cystic fibrosis increased in both countries between 1990 and 2013; however, in 1995 and 2005, survival in Canada increased at a faster rate than in the United States (P < 0.001). On the basis of contemporary data from 2009 to 2013, the median age of survival in Canada was 10 years greater than in the United States (50.9 vs. 40.6 years, respectively). The adjusted risk for death was 34% lower in Canada than the United States (hazard ratio, 0.66 [95% CI, 0.54 to 0.81]). A greater proportion of patients in Canada received transplants (10.3% vs. 6.5%, respectively [standardized difference, 13.7]). Differences in survival between U.S. and Canadian patients varied according to U.S. patients' insurance status.
Annals of Internal Medicine, March 14, 2017

Dr. Anne Stephenson is lead author on the study comparing survival rates in Canada and the U.S. for cystic fibrosis patients. (CBC)

We hear endlessly how it is that most Americans have no interest whatever in having their nation adopt a universal health-care system providing equal access to all citizens, as a social welfare provision of the state. Americans believe that whatever it is they do in any discipline is superior to how nation-counterparts in the developed world manage their affairs. And Canada's universal access to health care as a government-provided duty to its citizens defies the capitalist free enterprise system, so no thank you, very much.

A study just published in the Annals of Internal Medicine renders some extremely interesting data from neutral scientific investigation. Summing it up, Canadian patients with cystic fibrosis enjoy a median lifespan that is ten years in excess of the lifespan expectation of their American CF peers. An inherited genetic disease, CF was 'discovered' in 1938, and therapies that help to raise quality of life to a hoped-for level, along with life expectancy are still in the initial stages.

It is a dread disease, one that severely impairs the lungs and impacts on other bodily functions. The new study was meant to investigate published research to date, to attempt to determine just why it is that differences in lifespan outcomes exist for patients in Canada and the United States. Funded by the U.S. Cystic Fibrosis Foundation, fifty percent of the study's authors are Toronto-based researchers, with the lead author being Anne L. Stephenson, of St. Michael's Hospital in Toronto.

In 1960 the survival rate for CF sufferers was about ten years, and it was raised to thirty years by 1990. In 1994 the United States saw a slightly better survival rate for American CF patients than Canada, but for some unknown reason the Canadian median-survival-age measure began to surge ahead, and from then on began accelerating around 2005. In the period from 2009 to 2013 the estimated median lifetime of Canadian CF patients was 50.9 years whereas for American patients it was 40.6.

The researchers looked for telling differences in the CF databases of the two countries but that revealed nothing. They hypothesized that patients in the U.S. database might be likelier to have a more severe form of the disease, and perhaps be more susceptible to opportunistic infections; even that the specific gene defects were of a different mix. They came up empty, finding nothing to distinguish an advantage for Canadian patients over Americans.

Canadians can count on better care in managing their cystic fibrosis due to the universal health care system, yet Americans who are covered by Medicare or Medicaid do no better in the U.S. than those who lack insurance. There is one thing that has been seen to advantage CF sufferers and that was the high-fat diet for young CF patients that was adopted in the 1970s in Canada, now regarded as the best regimen, one that the United States arrived at at a much later date. Now it's theorized that in mid-life survival for Canadians who were given that optimum diet it might have played a role.

Another factor is lung transplants, where it seems that Canadian transplant recipients are enabled to live quite a bit longer than doctors had anticipated would be the case. While the U.S. uses a nationwide "lung allocation score" system and has since 2005, Canada uses lungs for surgical transplants locally, as they become available, leading the study authors to speculate whether this too may be involved in the longer Canadian lifespan, since under their system, American CF patients are given fewer transplant opportunities.

Erick Bauer, who was diagnosed with CF at age five, poses for a photo at St. Michael's Hospital in Toronto on Monday, March 13, 2017. Canadians with cystic fibrosis have a median lifespan a decade longer than their U.S. counterparts and researchers on both sides of the border are trying to figure out why there's such a dramatic survival gap between the two countries. THE CANADIAN PRESS/Aaron Vincent Elkaim