Retailer-led sugar-sweetened beverage price increase reduces purchases in a hospital convenience store in Melbourne, Australia: a mixed methods evaluation

Background: Limited evidence has been gathered on the real-world impact of sugar-sweetened beverage price changes on purchasing behavior over time or in community-retail settings. Objective: Our aim was to determine changes in beverage purchases, business outcomes, and customer and retailer satisfaction associated with a retailer-led sugar-sweetened beverage price increase in a convenience store. We hypothesized that purchases of less-healthy beverages would decrease compared to predicted sales. Design: A convergent parallel mixed methods design complemented sales data (122 weeks pre-intervention, 17 weeks during intervention) with stakeholder interviews and customer surveys. Participants/setting: Electronic beverage sales data were collected from a convenience store in Melbourne, Australia (August through November 2015). Convenience store staff completed semi-structured interviews (n=4) and adult customers exiting the store completed surveys (n=352). Intervention: Beverages were classified using a state government framework. Prices of "red" beverages (eg, nondiet soft drinks, energy drinks) increased by 20%. Prices of "amber" (eg, diet soft drinks, small pure fruit juices) and "green" beverages (eg, water) were unchanged. Main outcome measures: Changes in beverage volume, item sales, and revenue during the intervention were compared with predicted sales. Statistical analyses: Sales data were analyzed using time series segmented regression while controlling for pre-intervention trends, autocorrelation in sales data, and seasonal fluctuations. Results: Beverage volume sales of red (-27.6%; 95% CI -32.2 to -23.0) and amber (-26.7%; 95% CI -39.3 to -16.0) decreased, and volume of green beverages increased (+26.9%; 95% CI +14.1 to +39.7) in the 17th intervention week compared with predicted sales. Store manager and staff considered the intervention business-neutral, despite a small reduction in beverage revenue. Fifteen percent of customers noticed the price difference and 61% supported the intervention. Conclusions: A 20% sugar-sweetened beverage price increase was associated with a reduction in their purchases and an increase in purchases of healthier alternatives. Community retail settings present a bottom-up approach to improving consumer beverage choices.