Impact on alcohol selection and online purchasing of changing the proportion of available non-alcoholic versus alcoholic drinks: A randomised controlled trial

Abstract

Background Increasing the availability of non-alcoholic options is a promising population-level intervention to reduce alcohol consumption, currently unassessed in naturalistic settings. This study in an online retail setting aimed to estimate the impact of increasing the proportion of non-alcoholic (relative to alcoholic) drinks, on selection and actual purchasing of alcohol. Methods Adults (n=737) who regularly purchased alcohol online were randomly assigned to one of three groups: Higher Proportion of non-alcoholic drinks available (75%); Same Proportion (50%); Lower Proportion (25%). Participants selected drinks in a simulated online supermarket, before purchasing them in an actual online supermarket. The primary outcome was the number of alcohol units selected (with intention to purchase); secondary outcomes included purchasing. Findings 607 participants completed the study and were included in the primary analysis. The Higher Proportion group selected 10.0 fewer alcohol units than the Lower Proportion group (-32%; 95%CI -42%,-22%) and 7.1 fewer units compared to the Same Proportion group (-25%; 95%CI -36%,-13%), based on model results in those selecting any drinks containing alcohol (559/607). There was no evidence of a difference between the Same Proportion and Lower Proportion groups (2.9 fewer units, -9%; 95%CI -22%,5%). For all other outcomes, alcohol selection and purchasing were consistently lowest in the Higher Proportion group. Interpretation This study provides evidence that substantially increasing the proportion of non-alcoholic drinks - from 25% to 50% or 75% - meaningfully reduces alcohol selection and purchasing. Further studies are warranted to assess whether these effects are realised in a range of real-world settings.

Changing the assortment of available food and drink for leaner, greener diets

“…Although these studies focused on reducing selection of less healthy foods and soft drinks, the findings should apply to other products in principle, including alcoholic drinks. Preliminary results from a study of selection and purchasing of alcoholic and non-alcoholic alternatives from an online supermarket 35 support the findings of an earlier study of hypothetical selection in which participants were asked to select “one drink you would like to drink today.”36 Decreasing the proportion of alcoholic drinks available from 75% to 50% and 25% increased the proportion of non-alcoholic drinks selected (non-alcoholic beers and wines and soft drinks) from 24% to 32% and 45% respectively 35…”

Impact of health warning labels and calorie labels on selection and purchasing of alcoholic and non-alcoholic drinks: a randomised controlled trial

“…For example, ‘cart abandonment’ – where people do not purchase items they put in their shopping cart – is common in online (including supermarket) shopping contexts 37 . Retention to the point of actual purchasing was also significantly improved (from 66% to 77%) relative to our previous study using a similar protocol 38 , likely explained by an increased financial incentive and the refinement of study instructions. Additionally, the majority of participants that did purchase also went on to purchase the exact drinks they selected, indicating this study procedure is feasible and effective in measuring objective selection and purchasing in online shopping settings; future studies using a similar method should account for a similar degree of attrition.…”

“…For example, 'cart abandonment' -where people do not purchase items they put in their shopping cart -is common in online (including supermarket) shopping contexts 37 . Retention to the point of actual purchasing was also significantly improved (from 66% to 77%) relative to our previous study using a similar protocol 38 , likely explained by an increased financial incentive and the refinement of study instructions.…”

Impact of health warning labels and calorie labels on selection and purchasing of alcoholic and non‐alcoholic drinks: A randomized controlled trial

“…shopping contexts [49]. Retention to the point of actual purchasing was also significantly improved (from 66% to 77%) relative to our previous study using a similar protocol [50], probably explained by an increased financial incentive and the refinement of study instructions.…”