Evaluation of Changes in Beverage Prices and Volume Sold Following the Implementation and Repeal of a Sweetened Beverage Tax in Cook County, Illinois

IMPORTANCE: Health taxes are policy tools used to reduce harmful consumption of products and raise tax revenue, and they may also be associated with signaling (ie, informational and educational) factors that enhance their impact. OBJECTIVES: To examine changes in prices and volume sold of sweetened beverages following the implementation and repeal of the Cook County, Illinois, Sweetened Beverage Tax (SBT) compared with the comparison site of St Louis County and city, Missouri, which did not impose a tax. DESIGN, SETTING, AND PARTICIPANTS: This study used interrupted time series analyses to assess changes in price and volume sold of taxed (based on beverage type and sweetener status) and untaxed beverages in Cook County compared with St Louis following the implementation of the SBT on August 2, 2017, and its repeal effective December 1, 2017. Statistical analysis was performed from January to June 2020. EXPOSURES: Implementation and repeal of the Cook County SBT. MAIN OUTCOMES AND MEASURES: Changes in taxed and untaxed beverage prices and volume sold. Nielsen food store scanner data were obtained for weekly volume and dollar amount sold of nonalcoholic beverage universal product codes (UPCs) for each site in supermarkets and mass merchandise, grocery, drug, convenience, and dollar stores. RESULTS: The analytic samples included 16 510 UPCs for volume and 2141 UPCs (balanced sample) for prices for 122 pretax weeks, 16 tax weeks, and 35 postrepeal weeks. Compared with St Louis, posttax implementation in Cook County resulted in a level increase in taxed beverage prices of 1.13 cents per fluid ounce (95% CI, 1.01 to 1.25 cents per fluid ounce), representing a slight overshifting, followed by a posttax repeal level decrease of −1.19 cents per fluid ounce (95% CI, −1.33 to −1.04 cents per fluid ounce), with no resulting change pretax to posttax repeal. Volume sold of taxed beverages in Cook County compared with St Louis exhibited a posttax implementation level decrease of 25.7% (β = −0.297; 95% CI, −0.415 to −0.179) and a posttax repeal level increase of 30.5% (β = 0.266, 95% CI, 0.124 to 0.408), with no net change in volume sold from pretax to 8 months after repeal. CONCLUSIONS AND RELEVANCE: This study using interrupted time series analysis found no net change in volume sold of taxed beverages following the implementation and repeal of the Cook County SBT, suggesting the tax had no signaling association. Repeals of such taxes may fully reverse their associations with reduced demand and harms associated with sweetened beverage intake.