Associations between the Sweetened Beverage Tax Implementation in Seattle, WA and Changes in Supermarket Interior Marketing Displays

Sugar-sweetened beverages (SSBs) are a significant contributor to added sugar intake, leading to implementation of sugar beverage taxes. SSB taxes may impact supermarket in-store marketing strategies, leaning either towards or away from taxed beverages. Our study aims to evaluate the changes in supermarket interior marketing displays one year after the implementation of Seattle’s Sweetened Beverage Tax, which went into effect January 1, 2018. This study used a quasi-experimental design with supermarkets in Seattle exposed to the tax, while supermarkets in a comparison area were unexposed. The outcome evaluated was number of SSB and non-SSB interior marketing displays at supermarkets before and after-tax implementation. We used Poisson regression difference-in-difference (DID) models to estimate the degree to which the interior marketing displays in Seattle change above and beyond the interior marketing displays in the comparison area. We found a decrease in average change of interior marketing displays for soda (DID= 0.80, 95%CI= 0.66, 0.98) and diet soda (DID= 0.74, 95%CI= 0.60, 0.91), and an increase for diet energy drinks (DID= 1.93, 95%CI: 1.11, 3.36). This evaluation found no significant changes in collective SSB and non-SSB interior marketing displays. There was little evidence supermarkets increased or decreased the number of interior marketing displays in response to the SSB tax.