Evaluating the impact of minimum unit alcohol pricing on purchasing behaviour by different social class and age groups in Wales: A controlled interrupted time series study.

Objectives: Alcohol consumption and its associated harms pose a significant challenge to public health in the UK. To address this issue, Wales implemented a Minimum Unit Price policy (MUP) in February 2020, setting a minimum price of 50p per UK unit of alcohol (10 ml/8 g). In this study we evaluate the policy's impact on alcohol sales metrics to gauge its effectiveness in improving public health outcomes.

Study Design: Controlled interrupted time series study.

Methods: Analysis was conducted on alcohol sales data from February 2016 to February 2022, using the Kantar WorldPanel dataset, which tracks household alcohol purchases. The study employed a difference-in-difference and dynamic differences approach with controls for year fixed effects and a control for COVID-19, comparing the impact of the MUP in Wales to England, where no policy was introduced. Key outcomes included mean spend on alcohol per shopping trip, mean price per litre, proportion of households purchasing each type of alcohol (penetration), and average volume of alcohol purchased (average weekly purchase in volume and spend).

Results: MUP was associated with reduced alcohol purchases, notably among drinkers under 28 favouring cheap high-strength alcohol like cider. Effects varied by demographics and alcohol type. Those aged under 28 decreased cider consumption by 50 % compared to England, possibly switching to lager, which saw a 33 % spending increase. Older consumers exhibit short-term price insensitivity. Additionally, there was a 1.33 percentage point rise in wine consumption among lower socioeconomic groups.

Conclusions: MUP in Wales changed purchasing behaviour, which should lead to public health benefits in the longer term. There were some interesting effects by age group and alcohol type.