Effects of a Sugar-Sweetened Beverages Tax on Caries in Italy: A Modelling Study

Introduction: Despite efforts to reduce sugar consumption, Italy continues to experience high levels of caries, particularly among 12-year-old children. The introduction of a sugar tax is one strategy that gained traction as a mean of curbing excessive sugar intake. This study aimed to assess the potential impact of a sugar tax on reducing caries prevalence through the analysis of two scenarios: a hypothetical implementation of the tax in 2008 (Scen₁), compared against actual 2017 data, and a projection of the effects of the planned 2025 tax extending to 2034 (Scen₂).

The evaluation utilizes a Markov model to evaluate the health and economic outcomes of a 20% ad valorem tax on sugar-sweetened beverages. Outcomes included the caries experience, as DMFT index and QALYs (Quality-Adjusted Life Year/s), direct dental costs, and indirect costs as forgone earnings due to care, assuming a 100% pass-through to consumers. A 3% annual discount rate was applied to all costs. Sub-analysis also included geographical macro-areas of Italy (North-West, North-East, Centre, South, Islands), based on main socioeconomic determinants. A probabilistic sensitivity analysis, involving a Monte Carlo simulation with 1,000 iterations, was conducted to assess the robustness of the model, generating estimates of mean values and 95% uncertainty intervals.

In Scen₁, the simulation suggested that a 20% ad valorem tax would have resulted in a 0.05 reduction of the DMFT, yielded a cost saving of EUR 18.5 million, and EUR 24,520 per QALY gained. The projected 2025-2034 implementation estimated to decrease the DMFT by 0.07, save EUR 38.6 million, and EUR 31,933 per QALY gained. Significant benefits were observed in southern Italy, an area with higher caries rates and lower dental care utilization, where the impact was pronounced in both scenarios.

Integrating a sugar tax into a broader public health strategy can significantly reduce caries and healthcare costs, especially in disadvantaged settings. These findings highlight the need for policymakers to pair sugar taxes with additional preventive measures for optimal public health outcomes.