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.