Effects of an Alcohol-Specific Sales Tax on Sexually Transmitted Infections

Background:Alcohol is a well-established risk factor for sexually transmitted infections (STIs). Increased alcohol taxes are known to decrease alcohol consumption and alcohol-related morbidity and mortality. Most previous studies have examined the effect of excise taxes. We investigated the effects of the 2011 alcohol-specific sales tax increase in the state of Maryland on statewide rates of two common sexually transmitted infections (chlamydia and gonorrhea).

Methods:We used an interrupted time series design to examine the effect of the 2011 alcohol tax increase in Maryland on new chlamydia and gonorrhea cases reported to the US National Notifiable Disease Surveillance System for January 2003 to December 2012 (n = 120 repeated monthly observations). We used Box-Jenkins autoregressive moving average (ARIMA) models with structural parameters to account for temporal trends. We assessed differential effects of the tax increase by age, race/ethnicity, and gender subgroups using a pooled time series approach.

Results: Following the Maryland alcohol-specific sales tax increase, gonorrhea rates decreased 21% (95% Confidence Interval = 8% to 34%), resulting in 1,500 fewer cases of gonorrhea each year statewide. Cohen’s d ranged from -1.24 to -1.42 depending on the model; thereby, indicating a strong effect of the tax increase on gonorrhea rates. We did not find a significant differential effect of the tax increase on STI rates across age, race/ethnicity, or gender subgroups. We found no evidence of the alcohol tax change influencing chlamydia cases or rates.

Conclusions: Findings reinforce prior studies demonstrating an effect of alcohol tax changes on STI rates and extend this finding from excise to sales taxes. The natural experiment presented in Maryland indicates alcohol tax increases appear to be an efficient strategy to prevent STIs.