Secondhand Smoke and
Progression of Atherosclerosis

Journal of the American Medical Association 1998;279:119-124

A new study claims that secondhand smoke contributes to progression of carotid artery atherosclerosis (a condition involving accumulation of fatty material under the inner lining of the arterial wall).

This conclusion is based on a study of 10,000 adults. Smoking exposure and intimal-medial thickness of the carotid artery (IMT) was evaluated at an initial visit. The change in IMT was then reassessed three years later.

Smokers were reported to have a 50 percent greater increase in IMT than never-smokers. And persons exposed to ETS were reported to have a 20 percent greater increase than those not exposed to ETS (whoever they are).

But (and as raised in the accompanying editorial) there is no proof that IMT is a valid marker for advancing atheroslcerotic disease. To date, only two studies report an association between increased IMT and cardiovascular disease.

Also, and most importantly, the study failed to show a relationship between the number of hours of ETS exposure and IMT. If the study hypothesis was true, one would expect such a dose-response relationship to exist.

According to the Merck Manual, atherosclerosis is associated with half of all deaths. Risk factors include high blood pressure, high blood cholesterol level, smoking, diabetes, obesity, lack of exercise, and advancing age.

Uncertain biological plausibility, no dose-response relationship and a host of other risk factors for a fairly common disease -- but a pretty certain conclusion by the study authors... I dunno...sounds like junk science to me.

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