BMJ  2003;327:E93 (4 October), doi:10.1136/bmjusa.02020003 (published 28 August 2002)

BMJ USA: Letter

RAPID RESPONSES FROM BMJ.COM

Confounding factors

This article originally appeared in BMJ USA

Editor—I may only be a second-year medical student, but I've seen enough evidence-based medicine examples over the previous year to be able to spot when I think somebody is jumping to the wrong conclusion when interpreting data.

Sargent et al found a higher smoking uptake among adolescents who had seen more incidents of smoking in movies during the study period. However, I suggest that this association merely reflects the fact that adolescent smokers socialize a lot in public, due to smoking bans in the home (by parents). The increase in social interaction leads them to become the sort of people who are more likely to go to the cinema more often, and thus be exposed to more incidents of smoking. Perhaps it is not the films that encourage people to take up smoking; rather, smoking encourages people to go out to the cinema more and socialize.

Imperial College, UK richard.hutchinson{at}ic.ac.uk

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Preliminary study does not justify sweeping policy

Editor—There are so many unaccounted variables in the study by Sargent that it is unwise to base sweeping legislative proposals on its findings. Many studies have found that adolescent and adult smoking is part of a constellation of high-risk and thrill-seeking behaviors, and this constellation may well include heavy popular media consumption—especially the sorts of movies where characters themselves engage in risky behaviors such as smoking. Just as violent individuals tend to prefer more violent media, so smokers may prefer movies where their behavior is depicted frequently and positively, while those disinclined to smoke may reject movies where a behavior they reject is depicted. Evidence for my counter-hypothesis is found in the finding by Sargent et al that the odds ratio for smoking in the highest-movie-exposed set of youths drops dramatically from 8.8 to 2.7 when the selected sociopersonal variables in the study are controlled for. This suggests that sociopersonal variables powerfully mediate the tendency of adolescents to attend movies where heavy smoking is depicted.

The chief objection, however, is the proposal by Action on Smoking and Health (ASH) and Dr Stanton Glantz (see BMJ USA p 72), among others, for legislated restrictions on youths attending movies in which smoking is depicted. Even assuming a way could be found to prohibit youths from seeing smokers in movies they want to see, consider the thousands of movies—including virtually all classic war, newspaper, crime, and comedy films—to which restrictions would apply. Are Dr Glantz and ASH suggesting that a 14- or 16-year-old must have a guardian to see "Casablanca," "Pink Panther," or "The Graduate"? A quick glance at the American Film Institute's 10 "Best American Movies of All Time" indicates at least eight would be restricted for youth under the proposed policy.

Setting age limits for films depicting smoking is simply too great a curtailment of young people's basic right to participate in their culture even given the policy's laudable goal of reducing smoking.

Sociology Department, University of California, Santa Cruz, Santa Cruz, CA 95061 mmales{at}earthlink.net

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