Monday, 14 February 2011

The Iowan heart mystery

Reported in Iowa's local press and elsewhere:

It's been two years since the Smoke Free Air Act went into effect in Iowa. It prohibits smoking inside all bars and restaurants. The University of Iowa says in the two years Iowa has been smoke free, Iowans reduced their risk of heart disease by staggering numbers.

"Hospital admissions related to heart disease is much less, including stroke after the Smoke Free Air Act," says Dr. Enrico Martin of the Iowa Heart Center.

Admissions have gone down 24%, according to the University of Iowa. In just months, heart attack cases are down 8%. Strokes are down 5%. It's all thanks to the simple action of moving smokers outside.

This would seem to be exactly the same story that was reported over a year ago:

A recent study from the UI and the Iowa Department of Public Health shows a 24 percent decrease in Iowa hospital admissions for coronary heart disease and a decrease in admissions for heart attacks and strokes since the state restricted smoking.

Why the second lease of life for this particular heart miracle?

Perhaps because the study in question has finally been published? No. It still hasn't been published in any journal, peer-reviewed or otherwise.

Perhaps because some real evidence has appeared bearing out these "staggering numbers"? No. As Michael Siegel showed last week, statistics for heart disease and stroke—which are available on the Iowa Department of Public Health website—show no correlation between the date of the smoking ban and declining rates of mortality from these diseases:

Overall, there has been no change in the heart attack death rate in Iowa since the smoking ban was implemented. This is in contrast to a 39% decline in the heart attack death rate in the eight years prior to the smoking ban.

What the State of Iowa's own data show is:

Heart disease mortality rate (per 100,000):

2007: 229
2008: 242.1
2009: 229.8

Major cardiovascular disease (number of deaths):

2007: 9,200
2008: 9,623
2009: 9,232

(The smoking ban commenced July 1 2008)

Insofar as this 'study' has been published at all, it was in a three-page quarterly newsletter printed by Johnson County Public Health back in October 2010. From this, we can see that the monthly admissions in the first year of the ban were compared to the average monthly admissions between 2005-08. This is not the best of methods since we can't see the long-term trend (which is usually downwards, but not necessarily).

As you can see from the graphs above (taken from the newsletter), the data for heart attacks do not provide compelling evidence of any post-ban effect. The rate fell by 8%, which is the same as the rate of decline for flu and pneumonia (which have yet to be linked to secondhand smoke). And since admissions for heart attack rose in the first six months after the ban, this looks more like random fluctuation than anything else.

The coronary heart disease data, on the other hand, suggest a remarkably steep decline which accelerated over time. As the newsletter pointed out, a comparison between June 2009 and June 2008 shows a 40% decline (the magic number of the Helena hypothesis).

There are more than a few puzzles here. Mortality figures are not to be confused with hospital admissions figures, but it's reasonable to expect a correlation between the two. There isn't here. It's also reasonable to expect a correlation between CHD data and heart attack data. Sure enough, there is a close correlation between CHD mortality and heart attack mortality in the official figures (table above), but not in the newsletter's admissions data.

The evidence is incomplete, but reports of a heart miracle in Iowa are inconsistent with the hospital data that is publicly available. Yet again.


Anonymous said...

I hope it never gets to the point where the question is asked ,we banned smoking.we banned drinking,
we banned junk food.
Why aren't people living any longer ?


Anonymous said...

Smoking DOES cause pneumonia.

Smoking may substantially contribute to the growth of influenza epidemics affecting the entire population
Smoking may substantially contribute to the growth of influenza epidemics affecting the entire population

Jackson said...

Some employer's, I think, are banning non smoking applicants who inhale cigarette smoke.

Anonymous said...

Today's Daily Express. Professor Wild, Prof of Medicine at Lpool University, Claims that the smoking ban had a marked effect on heart attacks (in an article about obesity).

Anonymous said...

Chris, just saw a video of you on youtube ( And I got to thinking about your example of heart disease rates of nonsmokers after a smoking ban. On, they state that, "Cigarette smoking and exposure to tobacco smoke cause more than 440,000 premature deaths each year in the United States (1). Of these premature deaths, about 40 percent are from cancer, 35 percent are from heart disease and stroke, and 25 percent are from lung disease (6). Smoking is the leading cause of premature, preventable death in this country."
So 100% of those who die prematurely will die of SHS? No one gets murdered? No on dies unfortunately in a car wreck? No one commits suicide? No one dies of natural causes? From what I understand from everyone dies from tobacco exposure, so what is the point of not smoking?