The Effect of Alcohol Packaging Size and Strength on U.K. Alcohol Consumers' Classification of Alcohol Products as Containing a Single or Multiple Drinks

Objective: Reductions to the size and strength of alcohol products prompt reductions in alcohol consumption, although these effects may be limited to single drinks rather than packages that contain multiple drinks. This study investigated what product characteristics predict whether a product is seen as a single drink and seeks to identify the thresholds beyond which products are considered to contain multiple drinks. Method: Ninety-four U.K. drinkers from the prolific participant panel categorized 250 alcohol products with varying packaging sizes and strengths into single or multiple drinks. We used multilevel logistic regression to investigate whether packaging size, strength, total alcohol content, and container type predicted the likelihood that products were classified as a single drink across five drink types (beer, cider, ready-to-drink, spirits, wine). We used receiver operating characteristics curve analysis to identify the point at which products become too large or too strong to be considered a single drink by most drinkers. Results: Larger products, bottled drinks, products with higher alcohol by volume (ABV), and higher alcohol content were more likely to be classified as containing multiple drinks. We report thresholds for packaging size, ABV, and total alcohol content where products switch from being seen as a single drink to containing multiple drinks. The thresholds did not significantly differ between low-risk and increased risk drinkers. Conclusions: The reported thresholds can help researchers and policy makers encourage more accurate self-monitoring of alcohol consumption. Future research should test whether single drink classifications moderate the effect of packaging size and strength reductions on alcohol consumption. Public Health Significance Statement This study showed that the size, strength, and total alcohol content of alcohol products sold in U.K. stores affect whether these products are considered to contain a single drink or multiple drinks. We report the different thresholds after which products are too large or too strong to be considered to contain a single drink. These thresholds can be used to encourage more accurate self-monitoring of alcohol consumption and to inform the development and evaluation of future interventions related to the size and strength of alcohol products.