Friday, 12 August 2011

Selecting studies to scare smokers

Here's another one. Your risk of AF (atrial fibrillation) increases when you smoke.

Regardless of the fact that most people, probably correctly, perceive smoking as a health threat, new stories about how bad tobacco is come out daily.

But we know that. Stories about smoking roll off a production line, because there is a ready market for them. We also know that the mass market exists for stories that at least appear to give a result that makes tobacco appear more dangerous. We know that studies are censored at birth.

The same goes for secondary smoke. The diagram below comes from this story on heart attacks – the heart attack miracle that occurred in the year following the implementation of smoking bans everywhere from Scotland to Montana. Except (1) there is no evidence of any follow-up studies to show a sustained effect, (2) the figures frequently disagreed with routine statistics and (3) only the localities that did show a drop in heart attacks featured in published studies. The figure shows the range of results from all localities with comprehensive smoking bans, and the results clearly fail to show that smoking bans always result in a drop in heart attacks.

Chris's post shows more detail. We can be sure that for every study showing us the dangers of smoking and secondary smoking, there are studies or potential studies with results that anti-smokers would prefer us not to know.

This does not mean that there is no risk attached to smoking, of course – just that we are not told of any benefits (although nicotine has been appropriated by the pharmaceutical industry and so is regarded as having benefits), and we may be misled as to the scale of the risk. The study of AF linked above, for example, shows risk doubling, i.e. a risk factor of 2 – still a low risk.

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