Reports are once again lighting up with a new study about smoking bans triggering a sudden drop in heart attack rates. Here’s Sunday Times reporter Jonathan Leake:
The ban on public smoking has caused a fall in heart attack rates of about 10%, a study has found.
Researchers commissioned by the Department of Health have found a far sharper fall than they had expected in the number of heart attacks in England in the year after the ban was imposed in July 2007.
In Scotland, where the ban was introduced a year earlier, heart attack rates have fallen by about 14% because of the ban, separate research has shown. Similar results are expected in Wales where a third study is still under way. […]
“We always knew a public smoking ban would bring rapid health benefits, but we have been amazed by just how big and how rapid they are,” said John Britton, director of the UK Centre for Tobacco Control Studies at Nottingham University.
I’d love to dig into this study and find out how they got these numbers. The problem? As Michael Siegel explains, there is no study:
It turns out that there is no “study” to behold. The “study” appears to merely be a work in progress that has not yet been published or even submitted for publication, yet its results and conclusion were widely disseminated through the media. In other words, this is yet another example of what I call “science by press release.”
It appears that the conclusions of the study have been released to the media, but that the actual research itself is not being made publicly available. The study itself is not available, from what I can tell, on the University of Bath web site or the web site of the UK Centre for Tobacco Control Studies.
Therefore, it is impossible to judge whether the conclusions of the study are valid or not. And if the conclusions turn out to be unwarranted, then it will be too late to reverse them. The media have already disseminated the conclusion widely. Any correction given down the road would have little effect.
How these figures were calculated is therefore anybody’s guess. Christopher Snowdon suggests a few options based on previous manipulations in smoking ban studies and notes that the publicly available data from the NHS don’t support the conclusion:
We know that the heart attack rate fell by between 2 and 4% before the ban and by between 2 and 4% after the ban (see the HES website). To date, we only have the data for the first 9 months following the smoking ban, but that it is enough to go on. After all, if smoking bans immediately save lives, the first 9 months is where we would see the biggest drop.
“Smoking ban cut heart attacks in Scotland by 17 per cent”, researchers and politicians trumpeted to the world in September through press releases, a conference and interviews, all faithfully reported. It was the ban what done it, they said… until six weeks later when official data halved the drop — to 8 per cent — against a trend immediately before the ban of a 5 or 6 per cent drop, and a fall a few years ago of 11. All of which makes it hard to be sure what, if any, effect the ban really had. The researchers went strangely silent.
Leake quotes numerous experts who favor the unpublished study and not a single critic despite the thrashing that so many similar studies have taken. This is the sort of lazy journalism we’ve seen repeatedly in the field of tobacco regulation, where researchers can make any outlandish claim against smoking without fear of skepticism from gullible reporters. I don’t expect intellectual integrity from anti-tobacco activists, but we should demand better from the press.
Update 9/15/09: Now even ASH has backed away from this claim, saying “We have heard that the figures reported in the Sunday Times yesterday (and now circulating elsewhere) are not based on any research conducted to date.”