Impact of the demerit point system on road traffic accident mortality in Spain

Background To assess the effect of the Demerit Point System (DPS), introduced in Spain on 1 July 2006, on the number of fatalities due to road traffic accidents, using a methodology that controls for the seasonal variation and trend in the data series. Methods Time-series analysis by ARIMA models of 29 113 fatalities in road traffic accidents (at the accident scene or within 24 h thereafter), between January 2000 and December 2007. The model permitted estimation of an intervention parameter, together with its 95% CI, to calculate the number of fatalities that would have occurred if the DPS had not been implemented, after controlling for the effect of other measures introduced in 2004. Results It was estimated that 618 persons (95% CI 259 to 977) would have died in traffic accidents in the 18 months after implementation of the DPS had it not been in effect, which represents a reduction of 14.5% (95% CI 6.1% to 23.0%) from a total of 4252 deaths. Conclusion Implementation of the DPS in Spain has led to a significant reduction in the number of traffic accident deaths in the context of a downward trend after the implementation of the 2004 measures.