Impact of sugar-sweetened beverage taxes on price, import and sale volumes in an island: interrupted time series analysis.

Objective: To evaluate the impact of changes in import tariffs on sweetened beverages.

Design: Interrupted time series analysis was used to examine sweetened beverage tariff increases of 40-60 % in 2008 and to 75 % in 2012, and an approximately 11 % decrease in 2014 when an excise tax replaced the tariff. Post-tax trends were compared with a counterfactual modelled on the pre-tax trend for: quarterly price of an indicator beverage, monthly beverage import volumes (both 2001-2017) and quarterly sales volumes (2012-2017). In a controlled analysis, taxed beverage imports were compared with a sugary snacks control.

Setting: Cook Islands.

Participants: NA.

Results: In the first year, after the 2008 tariff increase the price of the selected indicator soft drink increased by 7·3 % (95 % CI 6·3 %, 8·3 %) but after the 2012 tariff increase it decreased by 13·9 % (95 % CI -14·9 %, -12·8 %). At the same time, the import volumes of taxed beverages decreased by 13·2 % (95 % CI -38·1 %, 17·8 %) and 2·9 % (95 % CI -41·6 %, 72·5 %), respectively, and decreased by 24·8 % (95 % CI -36·9, -9·8) and 10·2 % (95 % CI -37·1, 37·5) in the controlled analysis. After the 2014 tax decrease, the price of the indicator soft drink decreased by 23·6 % (95 % CI -26·0 %, -21·1 %), sweetened beverage imports increased by 4·5 % (95 % CI -39·5 %, 156·0 %) and sales of full-sugar soft drinks increased by 31 % (95 % CI -21 %, 243 %).

Conclusions: The increased import tariffs on sweetened beverages appeared to be effective for reducing import volumes, but this was partly reversed by the reduced tax/tariff in 2014.