Wednesday, May 24, 2006

National Anti-Smoking Groups Instructed Organizations to Use Helena Conclusions to Convince Public that Smoking Bans Immediately Reduce Heart Attacks

Three major anti-smoking organizations - the American Cancer Society, the International Union Against Cancer, and the Campaign for Tobacco-Free Kids - urged anti-smoking groups to increase the emotional appeal of the secondhand smoke health hazard message by communicating to the public that smoking bans can virtually instantly reduce heart attacks among both smokers and nonsmokers, based on a finding that there were 16 fewer heart attacks in Helena during the first six months of the city's smoking ban.

In a strategy document entitled "Building Public Awareness About Passive Smoking Hazards," the American Cancer Society and International Union Against Cancer offer suggestions to anti-smoking advocates about how to increase the emotional appeal of secondhand smoke health hazard claims. The Campaign for Tobacco-Free Kids appears to also have been a part of this strategy guide, although it is not listed as a primary author but instead, referred to in the document's introduction:

"On behalf of the American Cancer Society, The International Union Against Cancer, the Campaign for Tobacco-Free Kids, and the many wise and experienced colleagues who contributed to this lengthy project, we are deeply pleased to offer this series of guides, Tobacco Control Strategy Planning to the global tobacco control community."

The guide was designed "to help advocates develop practical strategies to overcome specific barriers to effective tobacco control policies."

In the document, anti-smoking groups were instructed to use the claim that 30 minutes of secondhand smoke exposure causes hardening of the arteries, blood clots, reduced blood flow to the heart, heart attacks, and strokes in order to increase the emotional appeal of their messages, a point I have discussed previously.

Here, I will discuss another instruction given to anti-smoking advocates: "Another message that may encourage the public to take action concerns a 2002 case study conducted in Helena, Montana (USA). Researchers found that, in the six months following the enactment of a new smoke-free workplace law, heart attack frequency declined significantly.

This message is effective for several reasons.
  • It offers a positive indication of what can happen to public health when people stop smoking and breathing secondhand smoke in public places.
  • It indicates that a ban on smoking in public places can reduce the incidence of heart attacks for smokers and nonsmokers alike.
  • It demonstrates that the health benefits of clean indoor air ordinances are virtually immediate.
  • It provides more scientific evidence that smoke-free workplace policies improve health and save lives, which should encourage communities around the world to take action to protect the health of their citizens."

The Rest of the Story

As I commented in my previous post, I don't believe that the observed findings in the Helena study support a conclusion that the smoking ban caused an immediate and dramatic drop in heart attacks. It simply isn't clear that the 16 fewer heart attacks that were observed in Helena during the first six months after the smoking ban was in effect were not simply random variation in the heart attack data for Helena. In such a small city, there is tremendous underlying variability in semi-annual heart attack admission rates, and that study does not allow a causal conclusion to be made.

Moreover, I have previously argued that it is scientifically implausible that the Helena smoking ban could have reduced heart attacks by 40% within six months. Even if all smoking were eliminated in Helena completely, one would no more than about a 40% decline in heart attacks. So how could a smoking ban in bars and restaurants have created such a large effect?

Thus, I find it unfortunate that we instructed tobacco control advocates to use the Helena conclusion to try to increase the emotional appeal of the secondhand smoke message. Since we are always accusing the tobacco industry of shoddy science, I think it's important that we not use the same shoddy science. So I think more scrutiny should have been given to this conclusion before we instructed advocates to use this shoddy science to promote our agenda.

A few elements of the document are particularly disturbing. First is the statement that this study demonstrates that "a ban on smoking in public places can reduce the incidence of heart attacks for smokers and nonsmokers alike." Even if the Helena conclusion was valid, it does not indicate at all whether the reduction in heart attacks was due to reduced secondhand smoke exposure, reduced smoking, or both. No information on smoking status was collected, no data on changes in secondhand smoke exposure were presented, and no data on changes in smoking prevalence were put forth.

Second is the statement that the study "demonstrates that the health benefits of clean indoor air ordinances are virtually immediate." There are immediate health benefits from clean indoor air ordinances, but the Helena study doesn't demonstrate that reducing heart attacks by 40% is one of them.

The Centers for Disease Control and Prevention, in its commentary on the Helena study (see: Pechacek TF, Babb S. How acute and reversible are the cardiovascular risks of secondhand smoke? BMJ 2004; 328: 980-983), which his been widely cited as supporting the contention that 30 minutes of secondhand smoke can cause heart attacks in nonsmokers, points out critical limitations of the study and makes it clear that these findings are not conclusive and that more research is necessary before any conclusions can be drawn:

"Although the results of the study by Sargent and colleagues are consistent with the literature on the risks of acute myocardial infarction associated with secondhand smoke, the study has some important limitations. Firstly, it contains no data on actual exposures to secondhand smoke among residents or cases, and thus no data on the changes in exposure to secondhand smoke that may have occurred after the policy was implemented. It might be reasonable to assume that levels of important smoke toxins within public places in Helena covered by the ordinance dropped dramatically. This effect has been observed in other locations where similar policies have been implemented, with air quality measurements showing 80-90% declines in public places. Even if such declines also occurred in Helena, some proportion of non-smokers would still have been exposed in their homes, cars, or other enclosed places not covered by the ordinance. Thus, without more data, the proportion of non-smokers in Helena among whom exposures were significantly reduced during the six months that the ordinance was in effect cannot be known.

A second concern is that the geographical isolation of the city, while making this type of study feasible, also resulted in a small number of admissions for acute myocardial infarction. As reported elsewhere, the typical number of acute myocardial infarction events per month before the ordinance was only about six or seven and was highly variable, with the actual number per month ranging from none to about 10-12. Although conservative statistical analyses were applied to these data, due to the small number of events and the lack of data on changes in active smoking, random variation and factors other than secondhand smoke exposure may have contributed to the findings.

Finally, the observed effect (a decline of an average of 16 admissions for acute myocardial infarction for a six month period) was substantially greater than what might be expected. With smokers accounting for 38% of the admissions, we can estimate that about 25 admissions (40x0.62 = 24.8) were among former and never smokers during the equivalent six month period before the ordinance. Even assuming that the proportion of acute myocardial infarction cases among smokers was fairly constant across time, that all non-smokers were frequently exposed to secondhand smoke in public places, that virtually all this exposure was eliminated by the ordinance, and that all coronary heart disease risk related to this exposure was immediately reversed among non-smokers (that is, that risk dropped from 1.3 to 1.0), the maximum impact on admissions for acute myocardial infarction would be predicted to be about 18-19% (0.30x24.8 = 7.44; 7.44/40 = 18.6%) during the six months that the ordinance was in effect. Taking all of the above assumptions and issues into consideration, a more conservative estimate of the predicted reduction in acute myocardial infarction events might be 10-15%."

The shame of the whole thing is that we didn't have to lower ourselves to this level, we didn't have to abandon our scientific integrity, in order to accomplish what this document wants to achieve.

There are immediate health benefits of smoking bans on the health of restaurant and bar workers, and plenty of them. And they have nothing to do with avoiding heart attacks. And there are immediate health benefits to smokers who quit because of these policies.

We didn't need to stretch the science in order to communicate these messages effectively and to promote our agenda. We could have just stuck with the science, and with the plain truth.

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