RESUMO
OBJECTIVE: To assess the impact of the Philadelphia Beverage Tax on perceived beverage healthfulness, and awareness and opinions of the tax. DESIGN: Natural experiment SETTING: Small independent stores in Philadelphia (n = 61) and Baltimore (untaxed control site; n = 65) PARTICIPANTS: Shoppers in Philadelphia (n = 2,731) and Baltimore (n = 4,600) pre- and post-tax implementation. MAIN OUTCOME MEASURES: Perceptions of 4 beverages (unhealthy vs healthy/neutral), tax awareness, and tax opinions (oppose vs favor/neutral). ANALYSIS: Mixed-effects linear probability models estimated changes in perceived beverage healthfulness in Philadelphia, relative to Baltimore, following a difference-in-differences approach. Mixed-effects linear probability models estimated pre-post changes in tax awareness and opinions in Philadelphia-only. RESULTS: The probability of perceiving taxed beverages as unhealthy increased 2-years post-tax relative to Baltimore (regular soda: 5.7% [95% confidence interval (CI), 0.9-10.6], P = 0.02; diet soda: 7.7% [95% CI, 1.5-13.8], P < 0.001; sports drinks: 6.4% [95% CI, 0.4-12.4], P = 0.04), with similar changes at 1-year post-tax, whereas perceived healthfulness of untaxed 100% fruit juice did not change. Tax awareness was high at baseline (72%) and increased post-implementation; however, the probability of opposing the tax (22%) also increased over time. CONCLUSIONS AND IMPLICATIONS: Decreases in the perceived healthfulness of taxed beverages suggest the tax had a health-signaling effect. Consumer awareness and health education efforts could complement tax policies to enhance understanding of health risks.