Effect of Alcohol Label Designs With Different Pictorial Representations of Alcohol Content and Health Warnings on Knowledge and Understanding of Low-Risk Drinking Guidelines: A Randomized Controlled Trial
Abstract
Background and aims
The UK low-risk drinking [alcohol use] guidelines (LRDG) recommend not regularly having more than 14 units of alcohol per week. This study tested the effect of different pictorial representations of alcohol content, some with a health warning, on knowledge of the LRDG and understanding of how many alcoholic beverages it equates to.
Design
Parallel randomized controlled trial.
Setting
On-line, January 25 – February 1, 2019.
Participants
Participants (n = 7516) were English, aged over 18 years and consume alcohol.
Interventions
The control group saw existing industry-standard labels; six intervention groups saw designs based on: food labels (serving or serving and container), pictographs (servings or containers), pie charts (servings) or risk gradients. A total of 500 participants (~70 per condition) saw a health warning under the design.
Measurements
Primary outcomes: (i) knowledge: proportion who answered that the LRDG is 14 units; and (ii) understanding: how many servings/containers of beverages one can have before reaching 14 units (10 questions, average distance from correct answer).
Findings
In the control group, 21.5% knew the LRDG; proportions were higher in intervention groups (all P < 0.001). The three best-performing designs had the LRDG in a separate statement, beneath the pictograph container: 51.1% [adjusted odds ratio (aOR) = 3.74, 95% confidence interval (CI) = 3.08–4.54], pictograph serving 48.8% (aOR = 4.11, 95% CI = 3.39–4.99) and pie-chart serving, 47.5% (aOR = 3.57, 95% CI = 2.93–4.34). Participants underestimated how many servings they could have: control mean = −4.64, standard deviation (SD) = 3.43; intervention groups were more accurate (all P < 0.001), best performing was pictograph serving (mean = −0.93, SD = 3.43). Participants overestimated how many containers they could have: control mean = 0.09, SD = 1.02; intervention groups overestimated even more (all P < 0.007), worst-performing was food label serving (mean = 1.10, SD = 1.27). Participants judged the alcohol content of beers more accurately than wine or spirits. The inclusion of a health warning had no statistically significant effect on any measure.
Conclusions
Labels with enhanced pictorial representations of alcohol content improved knowledge and understanding of the UK’s low-risk alcohol use guidelines compared with industry-standard labels; health warnings did not improve knowledge or understanding of low-risk alcohol use guidelines. Designs that improved knowledge most had the low-risk alcohol use guidelines in a separate statement located beneath the graphics.