By Jacob Sullum
Last year, criticizing a CDC-commissioned report from the Institute of Medicine that endorsed highly implausible claims of immediate, substantial reductions in heart attacks resulting from smoking bans, I noted that the authors had ignored the most comprehensive study of the subject, which found no such effect. Now that study, which at the time of the IOM report was available as a working paper from the National Bureau of Economic Research, has been published by the Journal of Policy Analysis and Management.
Instead of looking at small cities with volatile hospital admission numbers—the M.O. of studies that linked smoking bans to dramatic reductions in heart attacks—the authors of the new study, led by Kanaka Shetty of the RAND Corporation, used nationwide data to see if smoking bans were associated with changes in hospital admissions or mortality. "In contrast with smaller regional studies," they write, "we find that smoking bans are not associated with statistically significant short-term declines in mortality or hospital admissions for myocardial infarction or other diseases." In fact, "An analysis simulating smaller studies using subsamples reveals that large short-term increases in myocardial infarction incidence following a smoking ban are as common as the large decreases reported in the published literature."
Since 2003, when activists began claiming that workplace smoking bans immediately cut heart attacks by 40 percent or more, I've been saying that some jurisdictions will see such drops purely by chance, while others will see no change or increases of similar magnitude. Before you can say that smoking bans are associated with short-term declines in heart attacks (leaving aside the biological plausibility of such a link), you have to show that the first phenomenon is more common than the other two.
Anti-smoking activists such as Stanton Glantz, preferring to cherry-pick examples that fit their theory, have never done that, and now we can plainly see why: It isn't true. Although heart attacks do decline in some places with smoking bans, there are just as many places where they rise. On average, the difference between jurisdictions with smoking bans and jurisdictions without smoking bans is essentially zero.
So how was the IOM committee able to claim "consistent" results in favor of the claim that smoking bans immediately reduce heart attacks? Two words: publication bias. Shetty et al. write:
We show that there is wide year-to-year variation in myocardial infarction death and admission rates even in large regions such as counties and hospital catchment areas. Comparisons of small samples (which represent subsamples of our data and are similar to the samples used in the previous published literature) might have led to atypical findings. It is also possible that comparisons showing increases in cardiovascular events after a smoking ban were not submitted for publication because the results were considered implausible. Hence, the true distribution from single regions would include both increases and decreases in events and a mean close to zero, while the published record would show only decreases in events. Publication bias could plausibly explain the fact that dramatic short-term public health improvements were seen in prior studies of smoking bans....
We show that positive and negative changes in AMI incidence are equally likely after a smoking ban, which suggests that publication bias, not outcome heterogeneity, explains the skewed results seen in prior reviews. The IOM and other policymakers have relied on the weight of the published literature when making decisions. However, it appears that publication bias did not receive sufficient attention. Our results suggest that only positive studies have been published thus far, and the true short-run effects of governmental workplace smoking bans would be more modest in the U.S. Inclusion of such unpublished negative studies might change the conclusions of the IOM and other decision makers on this issue.
Don't hold your breath. Hyperbolic claims about drops in heart attacks following smoking bans, like hyperbolic claims about the mortal danger posed by the merest whiff of tobacco smoke, fit the agenda of the anti-smoking movement too well to ever be re-evaluated simply because they happen to be a load of crap. If the activists and officials who have endorsed these claims were concerned about telling the truth, they would not have been so reckless to begin with.
Michael Siegel, who for years has been doggedly criticizing the myocardial infractions of his fellow anti-smoking activists, wonders, "Will anti-smoking groups share and/or publicize the results of this new study or will they simply ignore evidence that does not fit their pre-determined conclusions?" Siegel's tobacco policy blog, where he regularly points out the unacknowledged whoppers told in the name of a smoke-free society, supplies the answer.