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Critique 183: An unusual analysis of the association of alcohol consumption with mortality — 24 March 2016

The stated purpose of this new analysis was to determine whether misclassifying former and occasional drinkers as abstainers and other potentially confounding study characteristics underlie observed positive health outcomes for low volume drinkers in prospective studies of mortality. Unfortunately, the authors include in their analyses a number of old epidemiologic studies and do not acknowledge that when the “errors” that they have commented on in the past (such as including heavy ex-drinkers in the no-alcohol referent group) have been dealt with in the majority of studies over the past decade. The authors still exclude the vast majority of these well-done studies in their new meta-analysis. Results of essentially all studies that adjust for their concerns continue to show a significant and meaningful reduction in the risk of cardiovascular disease (CVD) and total mortality from the moderate intake of wine and alcohol.

Forum members note how very selective the authors are in choosing which papers to include in their new analyses: they identified 2,575 studies on the subject, analyzed 87, but then they found some reason to exclude almost all of these studies to reach a conclusion that “ . . . there was no significant protection for low-volume drinkers (RR = 1.04, 95% CI [0.95, 1.15])” based on what is apparently only 6 remaining studies! The paper ignores the comments by two other scientists (Roerecke & Rehm) who, like these authors, have in the past been very concerned that confounding and errors weaken the purported relation between alcohol and a lower risk of cardiovascular disease, but have more recently concluded: “For drinkers having one to two drinks per drinking day without episodic heavy drinking, there is substantial and consistent evidence from epidemiological and short-term experimental studies for a beneficial association with IHD risk when compared to lifetime abstainers. The alcohol-IHD relationship fulfills all criteria for a causal association proposed by Hill.”

The authors of the present paper also ignore the immense amount of experimental data, not only animal experiments but trials in humans, that have described the mechanisms by which moderate alcohol and wine intake have been shown to decrease essentially all of the risk factors for CVD, including low HDL-cholesterol, elevated LDL-cholesterol, endothelial dysfunction, coagulopathies, inflammation, abnormal glucose metabolism, and many others. The consistent finding of lower CVD risk among moderate drinkers in all well-done cohort studies is strongly supported by experimental evidence of the mechanisms.

In the opinion of Forum members, the present paper markedly distorts the accumulated scientific evidence on alcohol and CVD. As stated by one Forum member, “The biased selection of studies that are included undermines the value of the paper, but more importantly promulgates misinformation in the name of appropriate scientific method. Failure to acknowledge the robust body of knowledge that supports the opposite conclusion, and disqualification of extensive animal and cell culture studies that offer plausible biologic explanation of observed benefits, is unconscionable.”

The Forum concludes that the overwhelming body of observational scientific data, as well as an immense number of experimental studies, support the contention that, for most middle-aged and older men and women who choose to do so, the regular consumption of small amounts of an alcoholic beverage can be considered as one component of a “healthy lifestyle.” Such a habit has been shown to be associated with a lower risk of cardiovascular disease and of total mortality.

Reference: Stockwell T, Zhao J, Panwar S, Roemer A, Naimi T, Chikritzhs T. Do “Moderate” Drinkers Have Reduced Mortality Risk? A Systematic Review and Meta-Analysis of Alcohol Consumption and All-Cause Mortality. J Stud Alcohol Drugs 2016;77:185–198.

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.
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