Ireland's Sugar Tax: A Case Study In How Not to Build An Evidence Base for Health Policy

Ireland introduced a Sugar Sweetened Drinks Tax (SSDT) on the 1st May 2018, with a subsequent expansion of the beverages covered in 2019. This measure was introduced in an attempt to combat rising levels of obesity and overweight. Five years later Ireland’s Department of Health invited applications for an evaluation of the impact of the SSDT. This investigation was designed to determine if the SSDT was successful in realising two key objectives: (1) that individuals reduce consumption of sugar sweetened drinks by reducing the amount consumed or switching to healthier choices; (2) that industry reformulates products to reduce (not necessarily remove) levels of added sugar in the drinks products. However, no baseline information on consumption, prices, beverage availability, or beverage composition was collected. This deficit critically weakened attempts at evaluation of the impact of the SSDT. Government-funded ongoing cross-sectional and longitudinal health surveys were not optimised to support an evaluation of the SSDT, and relevant survey questions changed during this 5-year post tax implementation period, thus preventing their meaningful incorporation in any evaluation of the SSDT. Future health interventions must be accompanied by careful evaluation plans based on robust data collection and analysis.