Socioeconomic position and the effect of price interventions on healthier and less healthy food on food selection in a simulated food delivery app: a randomised controlled trial

OBJECTIVE: We examined the effects of price interventions on the healthiness of a hypothetical food order in a simulated online out-of-home food delivery app. DESIGN: The design was a randomised controlled trial, with four conditions (10% taxation of less healthy menu items; 10% subsidy of healthier menu items; a combination of taxation and subsidy; standard pricing) and recruitment was stratified by socioeconomic position (SEP). Primary outcomes were healthier vs less healthy main meal selected and total kilocalories (kcals) selected. SETTING: Participants selected a hypothetical evening meal from out of home food outlets on a simulated online food delivery app. PARTICIPANTS: N=3107 adult participants from the UK were randomised into taxation (n=750), subsidies (n=808), a combination of taxation and subsidies (n=769), and standard pricing (n=779). 57-58% of participants were higher SEP. RESULTS: There were no statistically significant effects of the pricing interventions on whether a healthy vs less healthy main meal was selected (e.g. taxation vs control OR 0.91 (95% CI 0.74, 1.12); subsidies vs control OR 1.08 (95% CI 0.89, 1.31)) or on total kcals selected (e.g. taxation vs control regression coefficient -44.31 (95% CI -95.90, 7.28); subsidies vs control regression coefficient -7.94 (95% CI -60.23, 44.35)). There was no evidence that effects differed by SEP. CONCLUSIONS: We found no convincing evidence that 10% changes in price of healthy and less healthy food in a simulated out of home food delivery app impacted on healthiness of food selected. Further research may benefit from examining effects of larger price changes and in real-world purchasing conditions.