Thursday 3 February 2011

Up to his old tricks

Professor Glantz finds a way to help smokers cut down to one cigarette a day

In yesterday's post I discussed harm reduction and the prospect of having more people doing something which is not very harmful balanced against the prospect of having fewer people doing something that is very harmful. The basic argument comes down to this:

Whether or not you have a few more, a few less, or about the same number of people using nicotine products, if they are doing so using products which are 90%+ safer, the overall effect on public health can only be positive. If they are 90% safer, you would need more than ten previously uninterested people to start using these products for every smoker who uses them to quit. If they are 99% safer (and this is the more scientifically probable estimate), you would need more than 100 previously uninterested people to start using these products for every one smoker who uses them to quit. Common sense tells us that this is simply not going to happen and only a delusional fruitcake could possibly think otherwise.

Enter Stanton Glantz from the University of San Francisco: mechanical engineer, epidemiologist, cardiologist, economist, statistician and now soothsayer. Is there no beginning to this man's talents?

Stan thinks—nay, has shown in the peer-reviewed journal Tobacco Control—that if snus was "heavily and successfully promoted as healthier and more socially acceptable than cigarette use" it would lead to the number of people smoking cigarettes in the US leaping from 23.1% to 30.1%, with two-thirds of these smokers also being users of snus. Therefore, he reckons that:

Promoting smokeless tobacco as a safer alternative to cigarettes is unlikely to result in substantial health benefits at a population level.

To arrive at this counterintuitive conclusion, the great man has to demonstrate two things.

  • The honest (or, as he puts it "aggressive") marketing of snus as healthier and more socially acceptable would lead to a huge surge in snus consumption, with half of all new users coming from people who otherwise would not use tobacco in any form
  • Snus is much more dangerous than scientists believe and is, in itself, a major health risk

To take the second of these propositions first, Glantz states that:

Smokeless use has been linked to oral cancer, oropharyngeal cancer, heart disease and pancreatic cancer.

This is technically true. Smokeless tobacco has, at one time or another been linked to all these diseases. But one by one these scares have been shown to be baseless. Only last week, a definitive study showed that smokeless tobacco does not cause pancreatic cancer. That study came too late to feature in Glantz's evaluation, of course, but claims about snus causing any of the other diseases were debunked years ago. There is some evidence that the types of chewing tobacco used in places like India and Africa may be associated with oral cancer and heart disease, but the 'snus causes oral cancer' myth lost all credibility a decade ago.

Levy et al report the results of an expert panel that estimated a 90% reduction in mortality risk when using low nitrosamine smokeless tobacco compared to cigarette smoking.

Not quite. That expert panel found that these products were 90-95% safer and that was at a time when snus was thought to be more dangerous than it is now.

What the panel did find was that 90% of Americans "held the belief that the cancer risk from using chewing tobacco was equal to that from cigarettes." This myth—promoted by alleged health campaigners for decades—has no doubt deterred untold numbers of tobacco users from switching to less hazardous alternatives. The expert panel said:

The risks of using LN-SLT products [that's low nitrosamine smokeless tobacco products like snus] therefore should not be portrayed as comparable with those of smoking cigarettes as has been the practice of some governmental and public health authorities in the past.

Which suggests support for giving consumers honest and accurate information about risk—what Glantz calls "aggressive marketing." Glantz continues:

Data from the multinational INTERHEART study, a large case-control study of acute myocardial infarction (AMI), indicate an association between chewing tobacco use and AMI (OR 2.23, 95% CI 1.41 to 3.52) that was 75% of the risk of smoking cigarettes (OR 2.95, CI 2.77 to 3.14) and that the risk of dual use was larger than smoking.

But the INTERHEART study wasn't a study of low nitrosamine products and, as its authors admitted, it was something of an outlier anyway. It was unusual in finding a statistical association with heart disease and truly extraordinary in finding such a high relative risk. One of the reasons for this was that it was dominated by studies of the aforementioned dodgy chewing tobaccos from the Third World. A slew of studies have shown that snus does not increase heart attack risk (although a question remains about whether it may be associated with a small increase in mortality risk for those who have heart attacks).

Another 2005 review of the health risks of smoking compared to snus found that the risk of heart disease associated with snus is about half that of smoking.

This refers to a study by Roth et al., who found nothing of the sort. What the study actually says is:

Of all the studies examined, the only study that showed snus users to be at elevated risk to any type of disease was Bolinder et al. (1994), which reported significant elevations for both cardiovascular disease and total mortality...

None of the three other studies of cardiovascular disease (Asplund et al., 2003; Hergens et al., 2005; Huhtasaari et al., 1992) reported elevated levels of cardiovascular disease among snus users compared to the levels in non-tobacco users...

Considering all these findings, the Bolinder et al. (1994) cardiovascular disease findings appear to be an anomaly.

Not quite the same thing as the risk of heart disease being "half that of smokers", is it? More like "exactly the same risk as nonsmokers." What Glantz is doing here is, to use the scientific term, lying and hoping no one checks his references. There are still some dear, naive souls who believe that the peer-review process weeds out blatant falsehoods like this. Bless 'em. This is Tobacco Control, for goodness sake. We should be thankful the peer-reviewers corrected Glantz's spelling and put the graphs the right way up.

That pretty much covers the attempt to make snus look like a major health hazard when it's not. The issue of estimating how many people would take up snus as a result of the "aggressive marketing" is a much simpler matter. Glantz picked some numbers out of the air and wrote them down with an air of breezy confidence.

He assumed that the "aggressive" approach to harm reduction would lead to a tenfold increase in snus use. That's not so unreasonable. Less reasonable is his assumption that half of the new users would be previously uninterested nonsmokers. And half of the smokers who started using snus would continue to smoke. And snus users have half the heart disease risk of smokers. And the effect of promoting snus would reduce the effect of smoking bans by 50%. In other words, whatever figures you've got, just half them. It's the scientific way.

Why pick those figures? Because if he picked different ones he'd end up showing that tobacco harm reduction saved lives, stupid. Somehow—I'm really not sure how— Glantz uses these wild, unfounded guesses to navigate his way to the following jaw-dropping conclusions:

  • The number of smokeless-only users will rise from 1.0% to 12.6%
  • The number of cigarette-only users will fall from 19.8% to 10.5%
  • The number of smokeless users who also smoke cigarettes will rise from 1.6% to 19.6%
  • Overall, the proportion of the American public who smoke cigarettes will rise from 23.2% to 30.1%.
  • Tobacco-related death and disease would increase by 26%

There is more to be said about this study but, seriously, did no one at Tobacco Control think that it was a tad improbable that the promotion of snus as a healthier and more socially acceptable alternative to cigarettes was likely to result in a dramatic increase in the number of people smoking cigarettes? Did no one involved in this study have any objection to using half-truths, wild estimates and outright lies to come to a nutcase conclusion that would never happen in a million years? Are there still that many drugs being taken in San Francisco?

Whichever way you look at it, when it comes to peddling junk, Stan is still the man to beat.


Dick Puddlecote said...

They're starting to look mighty ridiculous ... great, innit? :)

Kristin Noll-Marsh said...

Chris, great post and love reading your blog, but PLEASE switch to a better font color/background combo. Very hard for us old folks (and I'm only 43 yrs old) to read!

Christopher Snowdon said...

Is this better?

JJ said...

Do you by any chance, have a heavy blunt instrument that he can be paid a visit with?