German communist philosopher Karl Marx (1818-1883) would have turned 200 earlier this month. More than a decade ago, Marx was posthumously ‘diagnosed’ with hidradenitis suppurativa (HS), a skin disease consisting of “’furuncles, boils and carbuncles’”. Historical research by British dermatologist Sam Shuster revealed that Marx complained about them developing on his “posterior and near the penis”.

Well, let’s not dig too deep into the hypothesis that this illness may have influenced Marx’s scholarly works and political thinking. Like it or not, Marx continues to be an inspiration for economists, sociologists, philosophers, political scientists and historians. Nowadays, with junk science being the leading scientific discipline, it is no wonder that Marx also inspires lifestyle epidemiologists. Two of them, Rudolf Happle and Arne König, from the Department of Dermatology at Marburg University, conducted “research” providing “evidence” for the cause of Marx’ skin disease.

„Smoking triggers hidradenitis suppurativa“ was their ground-breaking conclusion in an article in the British Journal of Epidemiology.  Sure, Marx loved his cigars, according to contemporaries, he was a “passionate smoker” – like many influential thinkers and revolutionaries. But how do the dermatologists link these two factors? They quote two surveys, one of them having been conducted by themselves, which state that a high percentage of HS patient were active smokers, higher than the mean of the population or that of the control group. Needless to say that such studies are of limited value due to the methods used (sampling, often non-randomized and a very small number of cases, omission of other risk factors etc.). But, combined with some “in vitro” study, enough “proof” was established for the two German scientists to complain about smoking not being recognized as a risk factor “of crucial causative significance” for HS.

This paper was quoted by some of the media, including the German Ärzteblatt. But they omitted the comment made by the above mentioned professor Sam Shuster, directly following the Happle/König article in the same issue of the BJD. “Happle and König go well beyond what is permissible from the evidence“, he explains in his witty and sharp analysis, pointing out that of the 63 patients mentioned in their own questionnaire study, only 32 started smoking before their skin disease, 10 of them took up the habit AFTER they began suffering from HS.  “While a smoking trigger makes an interesting variant on the smoking gun, the notion that smoking fires HS is a totally unsubstantiated allegation.” Even for the historical case of “patient” Marx, the authors’ conclusion cannot stand scientific scrutiny:  “If most of his confreres smoked, Marx’s smoking habit would have no statistical significance“. We would have to find more facts and data from that time.

For Shuster, the Happle/König contribution to tobacco bashing is a typical example of the abuse of statistical associations in epidemiology:

“Causal mechanics is something it cannot do, and frequent, inappropriate attempts serve only to produce the daily horror stories and lists of unsubstantiated associations that clog our journals and newspapers. Use of this bastard epidemiological substitute for science has spread like a cancer; it is doing much damage to genuine research, and has done much harm to the public’s belief in medical science. Old Marx was a tough thinker, very keen on scientific rationalism and he would have hated this development. But he also had a wicked sense of humour, and would have laughed it out of court – between bouts of his smoker’s cough.”

Wise words. We can only add that these methods are a standard procedure in anti-smoking research and that people using this “bastard […] substitute for science” might themselves be called “bastard substitutes” of scientists.

This article was originally published in 2008.

German version