Shinji Nakahara1, Masao Ichikawa. 1. Department of Preventive Medicine, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan. snakahara@marianna-u.ac.jp
Abstract
BACKGROUND: Japanese road traffic law was amended in 2002 and 2007 to increase the penalties for drink-driving in response to media coverage, publicity campaigns, and debates following high-profile alcohol-related motor-vehicle crashes in 1999 and 2006. OBJECTIVE: To test the hypothesis that the proportion of crashes involving drink-driving started to decline before the law amendments, because of changes in social norms and driver behaviour after the high-profile crashes. METHODS: In order to assess the impact of the cases in 1999 and 2006, time-series analyses were used to examine the trends in the proportion of crashes involving drink-driving, and whether there were abrupt changes in the level or slope at the expected time points, using monthly police data for the period between January 1995 and December 2008. RESULTS: In 1999, the proportion of alcohol-related fatal crashes in which the driver had a blood alcohol concentration (BAC) ≥0.5 mg/ml started to decline with a slope change of -0.09 percentage points per month (95% CI -0.15 to -0.03) but no level change, whereas there were no changes for drivers with a BAC <0.5. In 2006, the trends for drivers with a BAC ≥0.5 or <0.5 showed significant level declines of -3.1 (-5.0 to -1.2) and -1.7 (-2.5 to -0.9) percentage points, respectively, but no slope changes. CONCLUSIONS: Media coverage of high-profile crashes, and subsequent publicity campaigns and debates might have altered social norms and driver behaviour, reducing the proportion of alcohol-related crashes before the introduction of more severe penalties for drink-driving.
BACKGROUND: Japanese road traffic law was amended in 2002 and 2007 to increase the penalties for drink-driving in response to media coverage, publicity campaigns, and debates following high-profile alcohol-related motor-vehicle crashes in 1999 and 2006. OBJECTIVE: To test the hypothesis that the proportion of crashes involving drink-driving started to decline before the law amendments, because of changes in social norms and driver behaviour after the high-profile crashes. METHODS: In order to assess the impact of the cases in 1999 and 2006, time-series analyses were used to examine the trends in the proportion of crashes involving drink-driving, and whether there were abrupt changes in the level or slope at the expected time points, using monthly police data for the period between January 1995 and December 2008. RESULTS: In 1999, the proportion of alcohol-related fatal crashes in which the driver had a blood alcohol concentration (BAC) ≥0.5 mg/ml started to decline with a slope change of -0.09 percentage points per month (95% CI -0.15 to -0.03) but no level change, whereas there were no changes for drivers with a BAC <0.5. In 2006, the trends for drivers with a BAC ≥0.5 or <0.5 showed significant level declines of -3.1 (-5.0 to -1.2) and -1.7 (-2.5 to -0.9) percentage points, respectively, but no slope changes. CONCLUSIONS: Media coverage of high-profile crashes, and subsequent publicity campaigns and debates might have altered social norms and driver behaviour, reducing the proportion of alcohol-related crashes before the introduction of more severe penalties for drink-driving.