Seattle's sweetened beverage tax implementation and changes in interior marketing displays

Policymakers aim sugar-sweetened beverage (SSB) taxes at decreasing SSB consumption; however, little is known about their impact on beverage marketing in the retail environment. We assessed changes in interior marketing displays within large food stores before and after the implementation of Seattle's SSB tax. We used Poisson difference-in-difference (DID) models to estimate whether presence and variety of interior beverage marketing displays in Seattle changed from before to after the tax compared to displays in non-taxed comparison area stores, overall, and by beverage type. We found no significant changes in overall SSB or non-SSB interior marketing displays in Seattle versus the comparison area. There was less of an increase in displays for diet soda (DID 0.79, 90% CI 0.65, 0.97), and more of an increase in displays for diet energy drinks (DID 1.78, 90% CI 1.03, 3.09) in Seattle versus comparison area. There was mixed evidence that stores changed interior marketing displays in response to the SSB tax.