impact of a new law to reduce the legal blood alcohol concentration limit – a poisson regression analysis and descriptive approach

background: in chile, a new law introduced in march 2012 lowered the blood alcohol concentration (bac) limit for impaired drivers from 0.1% to 0.08% and the bac limit for driving under the influence of alcohol from 0.05% to 0.03%, but its effectiveness remains uncertain. the goal of this investigation was to evaluate the effects of this enactment on road traffic injuries and fatalities in chile. study design: a retrospective cohort study. methods: data were analyzed using a descriptive and a generalized linear models approach, type of poisson regression, to analyze deaths and injuries in a series of additive log-linear models accounting for the effects of law implementation, month influence, a linear time trend and population exposure. a review of national databases in chile was conducted from 2003 to 2014 to evaluate the monthly rates of traffic fatalities and injuries associated to alcohol and in total. results: it was observed a decrease by 28.1 percent in the monthly rate of traffic fatalities related to alcohol as compared to before the law ( p <0.001). adding a linear time trend as a predictor, the decrease was by 20.9 percent ( p <0.001).there was a reduction in the monthly rate of traffic injuries related to alcohol by 10.5 percent as compared to before the law ( p <0.001). adding a linear time trend as a predictor, the decrease was by 24.8 percent ( p <0.001). conclusions: positive results followed from this new ‘zero-tolerance’ law implemented in 2012 in chile. chile experienced a significant reduction in alcohol-related traffic fatalities and injuries, being a successful public health intervention.