Onset of a Declining Trend in Fatal Motor Vehicle Crashes Involving Drunk-driving in Japan

BACKGROUND In Japan, introduction of severe drunk-driving penalties and a lower blood alcohol concentration (BAC) limit in June 2002 was followed by a substantial reduction in fatal alcohol-related crashes. However, previous research suggests that this reduction started before the legal amendments. The causes of the decrease have not been studied in detail. METHODS Monthly police data on fatal road traffic crashes from January 1995 to August 2006 were analyzed using a joinpoint regression model to identify change-points in the trends of the proportion of drunk-driving among drivers primarily responsible for fatal crashes. We analyzed the data by BAC level (≥0.5 or <0.5 mg/ml), then conducted analyses stratified by vehicle type (car or motorcycle) and age group (<45 or ≥45 years) only for the proportion of those with a BAC of 0.5 mg/ml or higher. RESULTS Among all drivers, the proportion of those with a BAC of 0.5 mg/ml or higher and those with a BAC greater than 0 but less than 0.5 mg/ml showed a change-point from increase to decrease in February 2000 and in May 2002, respectively. The proportion of those with a BAC of 0.5 mg/ml or higher showed a change-point from increase to decrease in October 1999 among car drivers and in April 2000 among drivers younger than 45 years. There was no change-point among motorcyclists. A change-point from no trend to a decrease in January 2002 was observed among those 45 years or older. CONCLUSIONS The change-point identified around the end of 1999 to the start of 2000 suggests that a high-profile fatal crash in November 1999, which drew media attention and provoked public debate, triggered subsequent changes in drunk-driving behavior.