Bad weather and alcohol a life-threatening mix for traffic crashes

A significant increase in life-threatening alcohol-related traffic crashes occurs during adverse weather, compared to normal weather, according to new research from Sunnybrook Health Sciences Centre and published today in the BMJ (British Medical Journal).

"Drunk driving is a major cause of death yet physicians rarely counsel patients on the risks," said researcher Dr. Donald Redelmeier, a physician at Sunnybrook. "We wanted to test whether the risks of a life-threatening alcohol-related traffic crash were further accentuated by adverse weather.“ Bad weather also worsens glare, traction, and light backscatter that could additionally compromise how nearby traffic compensates for an impaired driver.

Redelmeier and Fizza Manzoor, a medical student at the University of Toronto, looked at 2,088 patients hospitalized at Sunnybrook for a life-threatening alcohol-related traffic crash from the past 20 years (1 January 1995 and 1 January 2015). The relative risk of a crash from adverse weather was tested by evaluating the weather at the place and time of the crash compared to the weather at the same place and time a week earlier and later.

The study found the risk of a life-threatening alcohol-related traffic crash was significantly higher during adverse weather compared to normal weather. The absolute increase in risk explained about 43 additional life-threatening crashes and almost $1 million in healthcare costs. The risk extended to diverse patients, and applied during both day and night. There was no significant increased risk from adverse weather for drivers negative for alcohol.

"Our findings suggest an opportunity for more public education, regulation and enforcement against drinking and driving," says Dr. Redelmeier. "An awareness of the risks might mean physicians should speak more frequently with patients about traffic safety, and counsel alternatives to drinking and driving. These harm-reduction plans should be discussed in advance since later intoxication will impair subsequent judgment."

Alcohol-related traffic crashes account for ten thousand deaths annually in North America. Almost all these deaths can be avoided by a small change in behavior.