Passive smoking

Editor—More than 140 readers responded to Enstrom and Kabat's paper and Davey Smith's editorial.¹,² Some of the passion and most of the science is captured in the letters above. What follows is a necessarily brief overview of the remaining ones. The debate started with some orthodox critical comment on the paper: the analysis underestimated the risk to passive smokers, was underpowered, distorted, poorly reported, placed out of context, or just plain wrong. The two main contentions were that a smoking spouse is a poor proxy for passive smoking (because everyone smoked in the 1950s, so people with non-smoking spouses were still exposed at work), and that many quitters are misclassified as smokers. Both would reduce the difference in mortality between exposed and non-exposed groups. In general, the criticisms were poorly substantiated; only four letters (3%) referred to actual data in the paper.

The discussions then widened to a number of more or less polite exchanges starting with the evils of the tobacco industry (too numerous to be repeated here), and the competing evils of drug companies that make nicotine replacement therapy. Neither side expressed their own view. Many readers were angry with the BMJ for publishing this study. More were angry about the “tabloid” cover on the journal, and the press release, which they said was sensational and misleading. Some thought the BMJ's editors were naive, others thought we were stupid, mad, or irresponsible, and a few suggested darker motives including raising our impact factor by publishing a citable paper. There were calls for a retraction, and one for an internal inquiry. Here are a few typical comments. “It is saddening that a prestigious publication such as BMJ has lowered its publication standards to the point of letting a piece of rubbish occupy its columns and amplifying it with a complaisant editorial.” “I cannot believe that a reputable journal such as the British Medical Journal can seriously print such a flawed study except to increase readership and create controversy” and “BMJ, what have you done?” The outrage had three themes: the study was bad for public health and should not have been published. Its conclusions were unreliable because the tobacco industry paid for them. And the methods and analysis were scientifically flawed. How could the paper have got through peer review? You can read our reviewers' comments, and an original, unedited draft of Davey Smith's editorial on bmj.com.

A dozen or so readers defended us. “You are to be congratulated for having the courage to publish research that, while politically incorrect and therefore destined to be excoriated by the anti-smoker lobbyists (many of whom work for anti-smoking organizations and therefore have obvious conflicts of interest even if they refuse to cite them) meets these criteria. Take solace that you are only being bashed verbally—Galileo paid a greater price for promulgation of his research that challenged the worldview of the catholic majority,” wrote the director of facilities at an American university. She had no competing interests to declare.

Neither did most other respondents, despite some giving tell tale addresses such as Smoke Free Educational Services Inc, Smoke Free Pennsylvania, Adults Saving Kids, and Forces International (an advocacy group for smokers). One reader thought the BMJ was being ironic, asking them for a competing interest statement, and a few others simply wrote “I enjoy smoking” or “I quit smoking.” Enstrom and Kabat wrote over 200 words explaining their funding and competing interests, but it wasn't enough. Both were accused of “swimming with sharks” and asked to clarify their dealings with the tobacco industry. One of them, Geoffrey Kabat, did so, adding, “To imply that skepticism about the `weak association' of passive smoking with heart disease and lung cancer is due to influence from the tobacco industry is simply wrong-headed. There is legitimate debate about the effects of passive smoking on heart disease and lung cancer. The evidence is not as uniform or as strong as the activists and scientists with extra-scientific agendas make out.” James Enstrom has clarified his dealings with the tobacco industry in BMJ/2003/084269. Richard Horton, the editor of the Lancet, concluded that the entire medical community is guilty of muddled thinking on conflicting interests.

Many letters were highly charged and hostile. “It is astounding how much of the criticism springs from Ad Hominem argument rather than from scientific criticism of the study itself,” wrote a “private citizen” from Philadelphia PA. “As a publisher of the leading Austrian medical online news service I feel quite embarrassed following the debate on this article. Many postings look more like a witch hunt than a scientific debate,” wrote another. It got bitter, and at times personal. A great read for anyone who enjoys a scrap. Disappointing for readers looking for a dispassionate appraisal of Enstrom and Kabat's study and its implications.