Impact of sugar-sweetened beverage taxes on price, import and sale volumes in an island nation: 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.