I intend to make the whole of September, and perhaps even the rest of the year, my “festival of 50” – an ongoing celebration of reaching my half-century. When I was younger I never used to pay much attention to birthdays. I’ve found the older I get, the more significant they become. “I’m still here” seems worth celebrating as you become more aware that it is far from certain you will be this time next year.
On top of that, in early October my latest book How The World Thinks is published, which is another great excuse for exercising the corkscrew. But as if to poop my party, a study was published last month which was widely reported to conclude that there is no safe level of alcohol consumption. Coincidentally, it came soon after a Guardian article in which I had in passing expressed scepticism about an earlier study claiming the same thing.
This latest finding was suspicious from the start because there have been numerous studies over very large populations that have suggested a J-shaped curve for alcohol consumption and all-cause mortality, meaning that non-drinkers die earlier than moderate drinkers, with death rates then rising as drinking becomes more frequent. Nonetheless, the summary of the new paper clearly stated “We found that the risk of all-cause mortality, and of cancers specifically, rises with increasing levels of consumption, and the level of consumption that minimises health loss is zero.”
I’m no medic but I reads the paper carefully and the “all-cause mortality” claim did not seem to stack up. The same summary indicated that the methodology was to conduct “a new meta-analysis of relative risks for 23 health outcomes associated with alcohol use” (my emphasis). This seemed to me a massive limitation. As scientist Ted Nield put it in a social media discussion, to look at only alcohol-related causes of death and conclude alcohol increases their probability is as surpassing as finding that “drowning increase with proximity to water”.
Odder still, road accidents were included among alcohol-related deaths, which is not a health issue if you don’t drink-drive. The explanation for this become clearer in a very good item on Radio Four’s More or Less in which it was made clear that the study was actually aimed at policy-makers, not individuals. This difference is critical. From a public health point of view, something that results in extra 1,000 premature deaths across the whole of society might be worth doing something about. As an individual, however, making a behavioural change could make a negligible difference to your life expectancy.
When you look at the actual risk to individuals suggested by the study (remembering this is exaggerated because of the focus on alcohol-related conditions), any reluctance to pour a glass of wine evaporates faster than alcohol in glüwein. Again on social media, David Millar pointed out that the study suggested “that out of a sample of 100,000 people an additional 338 develop alcohol related diseases because they consumed 5 units per day over those who did not drink alcohol. For non-drinkers in the same sample size, 914 would still develop the symptoms anyhow. 338 out of 100,000 is a small percentage, so whilst it’s a risk one needs to think if the odd tipple offers any other benefits that make it worth it.”
The definitive statistical put-down of the paper (or at least how it was reported) was published soon after by David Spiegelhalter, Winton Professor of the Public Understanding of Risk at the University of Cambridge. He highlights that even the press release attached to the report claimed that although “918 people in 100,000 who drank one alcoholic drink a day would develop an alcohol-related health problem in a year” the number of non-drinkers who would also develop one was 914.
It was good to find the More or Less team and Spiegelhalter confirm more precisely my own conclusions when interpreting the paper. It would be tempting to use this as a positive advert for the value of the critical thinking skills philosophy teaches. But I think it’s more complicated than that. In order to be able to spot the flaws in the reported findings, I also needed to be aware of common ways in which statistics are misunderstood. Philosophy didn’t teach me that. What it did do was to encourage the virtues of questioning and careful analysis. Studying philosophy is not enough: the virtues it nurtures need to be practised so that they become habits and our critical thinking skills gain tools from other disciplines too. One benefit of this for me is that I can now guiltlessly enjoy a celebratory couple of months.
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