How do we formulate low‐risk drinking guidelines if zero consumption is lowest risk?

Abstract

HOW DO WE FORMULATE LOW-RISK DRINKING GUIDELINES IF ZERO CONSUMPTION IS LOWEST RISK?This thought-provoking paper by Naimi and colleagues [1] packs a great deal into a few short pages. The meat comprises elegant analyses which (i) demonstrate why drinking more frequently may not be better for the health of 'moderate' drinkers and (ii) illustrate further the serious confounding in uncontrolled observational studies of alcohol consumption and health. The discussion, however, also serves a generous helping of relish by raising sharp questions about whether health benefits from moderate drinking exist, at what dosage they may be optimal and what this all means for the formulation of low-risk drinking guidelines. Naimi et al. [1] conclude that such guidelines should advise drinkers to not exceed about half of one standard drink per day on average. I will make one comment on the empirical findings, and then suggest a difficulty with their broader argument about low-risk drinking guidelines. In a restricted sample of people who on average drink within the US Dietary Guidelines, the authors report an inverse relationship between quantity of alcohol consumed on a drinking day and drinking frequency. This should not be surprising because, as they acknowledge, if the total consumption of a sample of drinkers is restricted in this way such a relationship is mathematically inevitable. What is important, however, is that this inevitable relationship has also influenced findings in other studies, which appear to show that increased frequency of drinking is associated with improved health (e.g. [2,3]). Thus they illustrate why such empirical observations should not be interpreted as evidence to encourage people who drink a little to do so more often. It is also important that Naimi's sample of drinkers comprise not just a small subsample, but 87.2% of all current drinkers in this large representative US national survey. The so-called 'moderate' drinking category for average consumption per day used in such studies contains the great majority of people who drink and who evidence substantial heterogeneity in drinking patterns and health risk profiles. The additional finding, that infrequent drinkers have significantly elevated health risk factors, adds further to worries about systematic biases in longitudinal studies of alcohol and health. Just one such worry is the bias introduced by the common practice of including 'occasional drinkers' in the abstainer reference group [4], e.g. anyone who drinks less than once a month.Naimi et al. [1] contribute to a groundswell of scepticism about the veracity of observed health benefits of light to moderate drinking thought to underlie the observation of a J-shaped risk relationship between level of drinking and risk of all-cause mortality (e.g. [4,5]). Other recent contributions include (i) the demonstration of systematic bias early in the life span caused by young adults who choose to be totally abstinent also having poorer health and lower incomes [6]; and (ii) the finding of apparent hea...

The unacceptability of evidence on acceptable risks

“…The Canadian process described by Shield et al . builds usefully upon this by describing a continuum of risk, separated into zones, rather than a single guideline level [4]. This shift is a welcome and long overdue development, given plentiful evidence of risks at all levels of alcohol consumption and no clear threshold above which risks increase especially rapidly [5].…”

Improving the epidemiology of low‐risk drinking guidelines is not enough

“…Shield et al . [1] draw upon the recent redevelopment of the Canadian Low Risk Drinking Guidelines to formulate some key principles that, they argue, should underpin future guidelines work internationally. This is an admirable attempt to further earlier work by Holmes et al .…”

Debating Shield et al.'s perspectives on how to formulate alcohol drinking guidelines

“…Shield et al . [1] present an important debate piece undergirding the recently adopted Canadian drinking guidelines. It is valuable to have provided the main rationales for four propositions that the expert panel developed in updating Canada's low‐risk drinking guidelines (LRDGs) that are now being implemented in Canada's 2023 Guidance on Alcohol and Health.…”

“…Although Shield et al . [1] pay some attention to drinking pattern in the discourse, the decision to not include this in the Canadian LRDGs is not much discussed, and implicitly this reflects a volume‐only view of risk. I suspect the expert group may have felt there was insufficient empirical evidence for the role of the pattern, by which the volume was obtained, but with this point I disagree, and at least in the United States, likely also in Canada, multiple important outcomes are associated with exceeding the weekly/daily combined guideline [12].…”

“…This may be so even for liver cirrhosis, where chronic drinking dominates, but acute episodes may affect important pathways [6]. Authors note that 21% of Canadians have a heavy episodic drinking pattern and tend to drink outside of meals [1]. It is possible that those now classed in the moderate risk category, with five or six drinks per week, would actually be at high risk for acute harms if they drank this amount in one sitting (not too unlikely); Knupfer [7] identified the myth of the steady drinker years ago, but this remains true; drinking patterns are highly predictive, for example, of AUD [8].…”