“Heart attacks plummet after smoking ban” declared the UK’s Sunday Times, as it reported that England’s smoking ban has “caused a fall in heart attack rates of about 10 per cent.” A few days later, the Scotsman upped the ante, informing its readers that “Smoking ban slashes heart attacks by up to a third across world.”
Tales of heart attacks being “slashed” by smoking bans have appeared with such regularity in recent years that it is easy to forget there is a conspicuous lack of reliable evidence to support them. It is almost as if the sheer number of column inches is a substitute for proof.
Mythical Study
The most recent reports are a case in point. Although The Sunday Times claimed a 10 percent drop in heart attacks, nowhere in the 500-word article was a source mentioned, and no one was quoted giving this figure.
The “study” the newspaper referred to does not exist, and the anti-smoking pressure group Action on Smoking and Health (ASH)–not renowned for downplaying the risks of passive smoking–went to the unusual lengths of posting a notice on its Web site the following day to point out “the figures reported in The Sunday Times yesterday (and now circulating elsewhere) are not based on any research conducted to date.”
Although the story quickly went around the globe, no one seems to know where the figure came from. It’s all rather strange. Basing journalism on anonymous sources is commonplace in the world of politics, but it is surely not necessary in the realms of science.
Cherry-Picked Data
The second story–reported by a host of news organizations, including the BBC–also had no new data to report. Instead it took its cue from an article in the journal Circulation, which examined previous smoking ban/heart attack studies. If nothing else, the Circulation paper offers an opportunity to reflect on just how feeble the collected evidence is on this issue.
The first study to claim smoking bans “slash” heart attacks was met with howls of derision when it was published in the British Medical Journal in 2004. Studying the modest population of Helena, Montana–where the number of monthly heart attacks seldom strayed into double digits–the study’s authors made the astounding claim that the town’s smoking ban had led to the rate of acute myocardial infarction (heart attacks) plummeting by 40 percent.
Dubbed the “Helena miracle” by a legion of skeptics, the 40 percent finding was damned by its very enormity. Since the authors were adamant that the drop was due to secondhand smoke (rather than smokers quitting), the finding required the reader to believe 40 percent of heart attacks in pre-ban Helena had been solely caused by passive smoking in bars and restaurants.
To understand quite how miraculous the Helena miracle was, one must bear in mind that around 10 to 15 percent of coronary heart disease cases are attributed to active smoking. That passive smoking could be responsible for a further 40 percent strains all credibility.
Hope for More Miracles
Despite the inherent implausibility of the hypothesis, further studies were swiftly commissioned. If smoking bans could be shown to immediately save lives, it would be a compelling reason to implement bans elsewhere and expand those already in place.
And since all that was required to “prove” the hypothesis was a rough correlation between a declining heart attack rate and the start of a smoking ban, the prospects were good. Heart attack rates had been falling for years in most countries, and there were plenty of smoking bans to choose from. The law of averages dictated another heart miracle would soon come to light.
Replicating Flaws
Flawed though it may have been, the Helena research was followed by several studies that displayed such a cavalier approach to the scientific process that they bordered on the comical. Researchers in Bowling Green, Ohio, for example, saw a large rise in heart attacks during the first year of the smoking ban. Sidestepping this awkward fact, they simply redefined year two of the ban as the “real” post-ban period, and since that year followed an abnormal peak, there was naturally a decline in the heart attack rate.
As a consequence, the researchers could triumphantly declare the smoking ban had led to a 47 percent reduction in heart attacks.
In the Piedmont region of Italy, there was an inconvenient rise in heart attacks among those over the age of 60 after the ban, so those people were simply ignored. In a study reported by the BBC (“Smoking ban reduces heart risk”), the researchers focused entirely on those under 60, thereby recording an 11 percent drop in cases.
Studies such as these form the basis for the recent reports of smoking bans slashing heart attacks by “up to a third.” The Circulation paper gathers them together and concludes that, on average, smoking bans cause rates of acute myocardial infarction to fall by 17 percent. It includes the studies from Ohio and Italy, as well as three studies that have never been published and have only been “reported at meetings.”
Big Study Ignored
The Circulation paper does not include a mammoth, published study of the entire United States, “Changes in U.S. Hospitalization and Mortality Rates Following Smoking Bans,” which concluded, “In contrast with smaller regional studies, we find that workplace bans are not associated with statistically significant short-term declines in mortality or hospital admissions for myocardial infarction or other diseases.”
Nor does the Circulation paper mention an unpublished paper that found no statistically significant fall in heart attacks amongst the entire populations of California, Florida, New York, and Oregon.
Bans Have No Effect
Perhaps the most remarkable aspect of the ongoing heart-miracle farrago is the eagerness to focus on small studies when complete hospital data is so freely available. It is extraordinary that no BBC journalist, for example, has thought of taking a few minutes to see how many people were rushed to hospital with acute myocardial infarction before and after the smoking bans of England, Scotland, and Wales.
If they did so, they would see that smoke-free legislation has had no tangible influence on heart attack rates at all.
The graphs below show the number of emergency admissions for acute myocardial infarction, with the arrow indicating the start of the smoking ban. What is abundantly clear in each case is that the number of heart attack admissions has been falling for some time. Far from causing further dramatic cuts in heart attack rates, the bans had no discernible effect.
Scotland
The press said: “Heart attacks drop by 17 per cent after smoking ban” (Telegraph).
The data say heart attacks were already in a long-term decline and accelerated little, if at all, after the ban:
Source: Information Services Division, Scotland. The arrow indicates when the smoking ban was implemented.
Wales
The press said: “The number of patients suffering a heart attack in Wales has fallen dramatically following the ban on smoking” (Wales Online).
The data say the drop was very slight and continued a decline that began before the ban:
Source: National Health Service, Wales. The arrow indicates when the smoking ban was implemented.
England
The press said: “Heart attacks plummet after smoking ban” (The Sunday Times).
The data say the drop was very slight and continued a decline that began before the ban:
Source: Hospital Episode Statistics Online. The arrow indicates when the smoking ban was implemented.
Hospital Data Conclusive
Publicly accessible hospital admissions data are like kryptonite to those who are so eager to believe in miracles. In most epidemiological studies pertaining to secondhand smoke, the raw data are not published. Here, the data are open to all and show quite clearly that the long-term downward trend in heart attacks has not been affected in any way by the implementation of smoking bans.
This provides such a simple and straightforward rebuttal to the heart attack “slashing” hypothesis that one wonders what level of hubris drives those who still espouse it.
The three graphs shown here cover a population larger than the sample groups in all the studies reviewed in Circulation combined, but no matter how much empirical evidence exposes the fantasy of the Helena miracle, it may be too late for the anti-smoking lobby to back down on this issue. Too many reputations are at stake.
After five years of covering these stories so uncritically, the same may be true of the media. One can scarcely blame newspapers for covering stories that offer such dramatic conclusions as the heart miracles. The irony is that if they dug just a little deeper, they might have found a more interesting, and more believable, tale of human folly.
Christopher Snowdon ([email protected]) is author of Velvet Glove, Iron Fist: A History of Anti-smoking, published by Little Dice. This article first appeared on spiked-online.com and is reprinted with permission.
For more information …
K. Shetty, “Changes in U.S. Hospitalization and Mortality Rates Following Smoking Bans,” National Bureau of Economic Research Working Paper No. 14790, March 2009: http://www.nber.org/papers/w14790.pdf
