Competing impacts of alcohol tax reductions and road safety policies on road traffic harm in Hong Kong: 15-year time-series analysis

Abstract

Background: Hong Kong, a special administrative region of China, cut ad valorem taxes on wine and beer from 80% and 40% respectively in 2007 and to 0% in 2008 to establish a global wine hub. Concurrently, Hong Kong strengthened road safety legislation in 2008 and progressively increased police traffic enforcement action from 2014. We evaluated the competing effects of alcohol tax reductions and road safety policies on road traffic harm. Methods: We used an interrupted time-series design on population-level data on road traffic injuries and collisions from 2004 to 2019 recorded by the Hong Kong (intervention) and Singapore (control) police forces. We fitted seasonal autoregressive integrated moving average (sARIMA) models on monthly data adjusting for underlying secular trends to assess slope and step changes at the intervention points. Analysis plan was pre-registered (doi.org/10.17605/OSF.IO/6JZPD). Results: Enactment of road safety legislation in June 2008 was associated with immediate step reductions in total collisions (8.1%, 95% CI: 5.3-11.0%), nonfatal injuries (6.7%, 95% CI: 3.0-10.3%), and serious/fatal injuries (14.3%, 95% CI: 7.3-20.8%). Progressively increasing police traffic enforcement action after the 2014 street protests (Umbrella Movement) were associated with continuous reductions in total collisions by 0.13% per month (95% CI: 0.04-0.22%), nonfatal injuries by 0.20% per month (95% CI: 0.07-0.32%), and serious/fatal injuries by 1.03% per month (95% CI: 0.80-1.25%). No comparable changes were observed in Singapore over the corresponding periods. Conclusion: Road safety policies were associated with continued reductions in road traffic harm despite weakened alcohol control and increased population alcohol consumption.