Evidence-based policy on road safety: the effect of the demerit points system on seat belt use and health outcomes

Abstract

Objective: To assess the effect of a demerit points system, introduced in Italy in July 2003, on the prevalence of seat belt use (intermediate outcome) and the number of road traffic deaths and injuries (health outcomes).

Design: Pre- and post-intervention regional observational study for seat belt investigation (April 2003, October 2004); national time-series analysis of road traffic deaths and injuries between 1999 and 2004 for health outcomes.

Setting: Veneto region, Italy.

Participants: 19 551 drivers, 19 057 front passengers and 8123 rear passengers estimated to be aged over 11 years were included in the investigation into seat belt use. 38 154 fatalities and 1 938 550 injured subjects were examined for the time-series analysis.

Interventions: Demerit points system.

Main outcome measures: The proportions of drivers and front and rear passengers observed to be using seat belts before and after the intervention; estimates of lives and injuries saved through the implementation of a penalty points system.

Results: The demerit points system was followed by an increase in observed seat belt use of 51.8% (95% confidence interval 48.7% to 54.9%) among drivers, of 42.3% (95% confidence interval 39.2% to 45.5%) among front passengers and of 120.7% (95% confidence interval 99.4% to 144.3%) among rear passengers. It is estimated that 1545 (95% confidence interval 1387 to 1703; p<0.0001) deaths and 91 772 (95% confidence interval 67 762 to 115 783; p<0.0001) injuries were prevented in the 18 months after the introduction of the legislation, i.e. an 18% reduction (1545/8570) in fatalities and a 19% reduction (91 772/473 048) in injuries.

Conclusions: The demerit points system is effective both in encouraging drivers and passengers to adhere to the law and in terms of health outcomes, substantially contributing to road safety.