The Canadian miracle in cystic fibrosis care takes centre stage — and it seems to be real

Posted on March 16, 2017 in Health Delivery System – Full Comment
March 15, 2017.   Colby Cosh

The Monday afternoon headlines seemed like a near-fatal blow to the prestige of American health care, if one were needed. A new study had disclosed that Canadian patients with cystic fibrosis, an inherited disease that impairs the lungs and snarls other bodily functions, have a median lifespan 10 years longer than that of Americans with the disorder.

Ten years! If you are like me, your first reaction to this information was: how could things possibly get so bad south of the border without anyone noticing? CF is fairly rare, and the patient populations are monitored closely in both countries. What are we doing that the Americans have not learned to?

If you want an answer, you won’t find it in this column, nor anywhere else known to medicine. But, yes, doctors treating cystic fibrosis had already noticed the big difference in lifespans for patients in the two countries. It actually comes to 11.7 years if you examine simple summaries of the data in the U.S. and Canadian national CF registries.

The purpose of new study, officially published on Tuesday in the Annals of Internal Medicine, was to scrutinize that known figure. (The study was funded by the U.S. Cystic Fibrosis Foundation, but half the authors are Toronto researchers, and the lead author is Anne L. Stephenson of St. Michael’s Hospital.) Is the 10-year-plus difference real, or could it be an artifact of data recording or reporting? And if it is real, is there a simple way to account for it?

For the busier reader, I will say here that yes, it looks real, and no, there is no simple explanation. As late as 1995, the United States was doing a smidgen better than Canada by the median-survival-age measure. For some reason, the Canadian performance surged slightly ahead at that time, and started climbing even faster around the year 2005. Over the five-year period from 2009-2013, the estimated median lifetime of CF patients in Canada was 50.9 years. For the U.S.A. it was 40.6 — which, by the way, is still a glorious triumph: that figure was close to 30 in 1990, and about 10 in 1960.

The first job of the researchers was to try to smooth out the tiny formatting differences in the two countries’ CF databases, but that process did not really change anything. Then they checked for differences between the actual populations. Perhaps patients in the U.S. database were more likely to have the disease in a severe form. Maybe they were more likely to have opportunistic infections. Maybe the mix of specific gene defects was different.

None of this seems to be the case, however, and when the databases were broken down into various subgroups, the Canadian advantage is present within all, and is of about the same magnitude. This is bad news: it means the researchers were not able to point to one particular kind of CF patient and cry “Eureka!”

There are some hints, and the authors highlight them in their concluding discussion. When the American patients were broken down into groups according to the kind of health insurance coverage they had, Canadians were not significantly ahead of Americans with private or employer-funded insurance. If anything we may be slightly disadvantaged.

No one can be surprised that Canadians who have cystic fibrosis get better care than completely uninsured Americans, but Americans covered by Medicare or Medicaid, federal insurance plans for the poor and the aged, do badly too. Canada’s portable cross-country care may be especially beneficial in the realm of a lifelong disease that runs in families.

No one can be surprised that Canadians who have cystic fibrosis get better care than completely uninsured Americans

Like most statistical phenomena, the lifespan difference is being noticed and studied at a time when it became especially prominent. That is in itself a reason to suspect it might regress, but there is another. Canada adopted high-fat diets for young CF patients in the 1970s, and that is now accepted as the best regimen. The U.S. was later in boarding that bus, so the spread in lifespans today may be reflecting better mid-life survival for Canadians raised on the optimum diet.

Cystic fibrosis is still a fairly recent discovery (1938), and while therapeutic controversies like the one over childhood diet have been settled, others are alive. One of those arguments concerns which CF patients, if any, are likely to benefit from lung transplants. Some doctors resist the whole idea of transplantation as a CF treatment, but the findings of Stephenson et al. confirm earlier hints that Canadian transplant recipients last far longer than anyone ever anticipated.

This could be an important key to the mystery. The U.S. adopted a nationwide “lung allocation score” system in 2005, while Canada still gives away donor lungs locally, in an ad-hoc way, as they become available. The authors wonder if this may have something to do with the acceleration of the Canadian lifespan advantage at around that time. It seems that the American lung allocation system leads to fewer transplants for CF patients — which may even be proper, if the score is well designed and the diverted lungs are helping other sick people more. In view of the headline-making lifespan data in the Stephenson study, however, that proposition would seem to need some very serious reconsideration.

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