Health warning labels and alcohol selection: a randomised controlled experiment in a naturalistic shopping laboratory

Background and aims: Health warning labels (HWLs) on tobacco products reduce smoking. There is an absence of evidence concerning the impact of alcohol HWLs on selection or purchasing in naturalistic settings. Using a commercial-standard naturalistic shopping laboratory, this study aimed to estimate the impact on selection of alcoholic drinks of HWLs describing adverse health consequences of excessive alcohol consumption. Design: A between-subjects randomised experiment with three groups was conducted: group 1: image-and-text HWL; group 2: text-only HWL; group 3: no HWL. Setting: A commercial-standard naturalistic shopping laboratory in the United Kingdom. Participants: Adults (n = 399, 55% female) over the age of 18 years, who purchased beer or wine weekly to drink at home. Interventions: Participants were randomised to one of three groups varying in the HWL displayed on the packaging of the alcoholic drinks: (i) image-and-text HWL (n = 135); (ii) text-only HWL (n = 129); (iii) no HWL (n = 135). Participants completed a shopping task, selecting items from a range of alcoholic and non-alcoholic drinks, and snacks. Measurement: The primary outcome was the proportion of alcoholic drinks selected. Secondary outcomes included HWL ratings on negative emotional arousal and label acceptability. Findings: There was no clear evidence of a difference in the HWL groups for the percentage of drinks selected that were alcoholic compared to no HWL (44%): image-and-text HWL: 46% (odds ratio [OR] = 1.08, 95% confidence interval [CI] = 0.82, 1.42); text-only HWL: 41% (OR = 0.87, 95% CI = 0.67, 1.14). Concordant with there being no difference between groups, there was extreme evidence in favour of the null hypothesis (Bayes factor [BF] < 0.01). Negative emotional arousal was higher (P < 0.001) and acceptability lower (P < 0.001) in the image-and-text HWL group, compared to the text-only HWL group. Conclusions: In a naturalistic shopping laboratory, there was no evidence that health warning labels describing the adverse health consequences of excessive alcohol consumption changed selection behaviour.