Effect of restricted retail merchandising of discretionary food and beverages on population diet: post-trial follow-up of a pragmatic randomised controlled trial.

Background: Healthy Stores 2020 tested a co-designed strategy restricting retailer merchandising of unhealthy foods in a community-level pragmatic, partially randomised, parallel group trial in 20 remote Australian Aboriginal and Torres Strait Islander community stores. We aimed to evaluate the impact of Healthy Stores 2020 on free sugar sales 24-weeks post-trial.

Methods: Twenty stores were randomly assigned by a statistician using a single sequence of random assignments to the intervention group, in which a strategy restricted merchandising of unhealthy food (either six or seven strategy components), or to a control group of usual retail practice. The trial was done in partnership with an Indigenous organisation operating in remote Australia. In the post-trial period (24 weeks), immediately following the 25-week RCT, intervention stores (n = 10) continued the strategy but with no external implementation support, and control stores (n = 10) continued usual practice. The primary outcome was impact on purchases (weekly sales data) of free sugars from all foods and beverages (g/MJ) using mixed models. Secondary outcomes included total food and beverage dollars and gross profit (AUD$) and strategy implementation (number of strategies with full implementation assessed via photographic data collected). Trial registration, ACTRN12618001588280.

Findings: We observed a difference in sales of total free sugars to energy between the treatment and control groups post-trial (-4.6%, 95% CI -7.1, -1.9). Between group differences in total food and beverage and gross profit dollars were 7.0% (0.9, 13.5) and 11.4% (4.6, 18.6), respectively. Two intervention stores had full implementation of all strategy components and eight intervention stores had compliance with at least four of the seven strategy components at post-trial end.

Interpretation: A health-enabling retail intervention showed an effect on sugar reduction in the post-trial period without adversely impacting profit.

Funding: Australian National Health and Medical Research Council.