Monday 15 April 2024

Tim Stockwell's relationship with evidence

Tim Stockwell, who has been running a one man crusade against the benefits of moderate drinking for 20 years, has been on a bit of a media tour recently. He got a feature in the New York Times two weeks ago and is currently in Scotland where he is gearing up for a talk at the Royal College of Physicians on Wednesday. The talk has been organised by the state-funded Scottish Health Action on Alcohol Problems (SHAAP) and the anti-alcohol Institute of Alcohol Studies. As the Herald reports...

Prof Stockwell's talk in Edinburgh on Wednesday is also expected to coincide with MSPs voting on a motion to increase Scotland's minimum unit price (MUP) levy from 50 to 65 pence.

How fortuitous! 

Stockwell's longstanding approach has been to clog up the search engines with meta-analyses that either cherry-pick the data or retrospectively adjust it to diminish the benefits of moderate drinking - I wrote about his most recent effort last year. In an interview with the Herald this weekend, he was still banging on about the sick quitter hypothesis which has repeatedly been shown to not explain the alcohol J-Curve

He then turns to minimum pricing, which he keenly supports. You may recall that Stockwell conjured up some evidence for this policy back in the day, claiming that a 10% increase in the minimum price of alcohol in a Canadian province led to a 32% reduction in alcohol-related deaths. This would be a remarkably large effect if true but, as data from his own research group showed, it was not remotely true.

Stockwell's approach to matters related to alcohol is refreshingly simple. If he wants something to be true, he says it is true, regardless of what the evidence says. Since most journalists are not familiar with the evidence and trust anyone who sounds like they might be a doctor (Stockwell's degree was in psychology and philosophy), this is more effective than you might think.

For example, there is good evidence from both the official evaluation and independent research that minimum pricing in Scotland did not make heavy drinkers reduce their alcohol consumption. A study in BMJ Open found that the heaviest drinking 5% of men drank more after minimum pricing was introduced. Even the people at Sheffield University who did the modelling for minimum pricing in the first place had to admit that "the introduction of MUP in Scotland did not lead to a decline in the proportion of adult drinkers consuming alcohol at harmful levels".
Stockwell doesn't believe this therefore he says that it ain't so.

He said he is confident that MUP has made a difference to heavy drinkers, despite some surveys suggesting they had not cut down. 

He said: "If you look at total sales data: 50% of the alcohol sold is consumed by heavy drinkers.

"You don't get population level reductions - a 3% total reduction in consumption compared to England and Wales - unless heavy drinkers are cutting down. It's mathematically impossible."

I don't wish to insult your intelligence, dear reader, but it is definitely not mathematically impossible.  

"All the surveys done, however good they seem, are observational studies - not control studies."

Control studies? Does he mean randomised controlled trials? How could you even design an RCT to measure this? Nearly everything we know about the risks of drinking comes from observational studies. Isn't it funny how Stockwell accepts these when they show risks but not benefits and demands an impossible burden of proof when the results don't suit his agenda.

"So it really has worked, especially in people with heavy alcohol use."

OK, bud.

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