Tuesday, 28 August 2012

Smoking ban miracle in Germany

Readers of this story recognise the holes in it. Researchers found a city where heart attack admissions have dropped following the introduction of a smoking ban, and quickly decided that it would help in building the case for a smoking ban, regardless of any other factors, such as the comprehensiveness of the ban and whether or not it did actually result in a reduction of so-called passive smoke exposure (rather than simply ensuring that people were exposed at home rather than in recreational venues).

The story says that the drop in heart attacks in Bremen was a 25 per cent drop and compares it to the drop of 2.4 per cent that the Department of Health found in England. A ten-fold disparity (as well as the huge disparities in population) in the figures must surely tell them something! but the figures of various heart attack drops are rattled off as if they proved, rather than cast a heavy shadow over the theory that smoking bans stop heart attack admissions.

A more accurate measure would have involved a larger population, across the whole of Germany. Why pick Bremen anyway – simply because the figures could be made to show a large drop? Small populations are more likely to produce startling variances for a wide variety of reasons.

An example of a study seeking to cover a wider population base is here. No statistically significant drops in heart attacks were found when studies were conducted over wider population bases using publicly available data on admissions, and employing appropriate controls.


Lysistrata said...

Indeed, Belinda.

A number of factors could explain the huge variance: perhaps patients were taken to a different A&E hospital; perhaps a local nursing home closed (that can skew figures enormously); perhaps the weather was unusually hot or cold in Bremen; perhaps as you suggest the variation was within too small a sample to be significant.

westcoast2 said...

I think the second sentence should read "...where the heart attack rate...."

Do they ever do follow up studies in towns where these miracles have happened?

Belinda said...

Corrected, westcoast2. I have never heard of any follow-up studies on heart attacks, and certainly not of Professor Jill Pell being able to sustain the fiction in Scotland.