The BMJ Today: Monday’s reflections on alcohol

wim_weberNothing seems more appropriate on a Monday than to think about the after effects of alcohol. We know that drinking too much is bad for health, but many have always taken comfort in the “fact” that moderate daily intake is associated with a lower cardiovascular risk. The question remains whether light to moderate drinking will actually reduce this risk. Observational studies cannot help us here, but a recent Mendelian randomisation study sheds new light on this controversy.

Mendelian randomisation studies are not randomised trials, but they use a genetic trait as a proxy, thus “randomising” populations into one with the “gene” and one without. The trick is finding an appropriate gene. In this recent paper from The BMJ, Michael Holmes et al used the A-allele of the ADH1B locus as an equivalent to being randomly assigned to drink less alcohol. Holmes and a great many colleagues, in a study of over 200 000 individuals, found that A-allele carriers drink less and have lower cardiovascular risk. They conclude that drinking alcohol, even light to moderate amounts, increases cardiovascular risk, and that prior observational evidence should be revisited.

Editorialist Maria Glymour explains elegantly why this new study is not the last word on this research question. So, no need yet to revise the NHS alcohol guidelines, which give us maximum daily intakes for women and men. The guidelines, however, do recommend that one group refrain from drinking alcohol completely: pregnant women.

Another recent Research paper has good news for this group: pertussis vaccination in the third trimester does not have any adverse effects related to pregnancy. Katherine Donegan and colleagues used the UK Clinical Practice Research Datalink to find more than 20 000 pregnant women who had received a pertussis vaccine and compared these women with an unvaccinated group. They found no differences in any serious events that can occur in pregnancy. This is good news, in the light of the recent increases in whooping cough cases, and the subsequent recommendation to vaccinate pregnant women in the third trimester.

In the news, Michael McCarthy reports that the US is now officially recommending not to screen asymptomatic people for carotid stenosis. I thought that this had already been abandoned since the two landmark trials showing that carotid endartectomy only benefits patients with symptoms and a stenosis of more than 70%. And even then, you have to select your surgeon carefully, finding one in a high volume centre with a 30 day stroke or mortality rate of less than 3%. McCarthy notes that in the US these carotid artery stenosis screening tests are commonly offered at health fairs and other settings.

Wim Weber is European research editor at The BMJ.