Effectiveness of ignition interlocks for preventing alcohol-impaired driving and alcohol-related crashes: a Community Guide systematic review.

A systematic review of the literature to assess the effectiveness of ignition interlocks for reducing alcohol-impaired driving and alcohol-related crashes was conducted for the Guide to Community Preventive Services (Community Guide). Because one of the primary research issues of interest--the degree to which the installation of interlocks in offenders' vehicles reduces alcohol-impaired driving in comparison to alternative sanctions (primarily license suspension)--was addressed by a 2004 systematic review conducted for the Cochrane Collaboration, the current review incorporates that previous work and extends it to include more recent literature and crash outcomes. The body of evidence evaluated includes the 11 studies from the prior review, plus four more recent studies published through December 2007. The installation of ignition interlocks was associated consistently with large reductions in re-arrest rates for alcohol-impaired driving within both the earlier and later bodies of evidence. Following removal of interlocks, re-arrest rates reverted to levels similar to those for comparison groups. The limited available evidence from three studies that evaluated crash rates suggests that alcohol-related crashes decrease while interlocks are installed in vehicles. According to Community Guide rules of evidence, these findings provide strong evidence that interlocks, while they are in use in offenders' vehicles, are effective in reducing re-arrest rates. However, the potential for interlock programs to reduce alcohol-related crashes is currently limited by the small proportion of offenders who participate in the programs and the lack of a persistent beneficial effect once the interlock is removed. Suggestions for facilitating more widespread and sustained use of ignition interlocks are provided.