Some prescription drugs increase risk of car crashes by 35%, say UBC researchers

Researchers at the University of British Columbia have found that prescribed anti-psychotics, benzodiazepines and high-potency opioids are associated with the highest increase in risk for road accidents.

The group's findings are included in a study published this week in the Lancet Public Health journal.

Jeff Brubacher, an author of the paper, associate professor in the department of emergency medicine at UBC and emergency room physician at Vancouver General hospital, hopes the study's results help people manage their risk when using the medications.

Brubacher said his team combined 20 years worth of police collision reports with prescription records, all without names attached, to determine which of 70 classes of medication were associated with the greatest risk of collision.

About 5 million drivers and 700,000 collisions were included in the data.

The class of drugs with the highest risk is sedative anti-psychotics, with a 35 per cent increased risk. That was followed by benzodiazepines (like Valium and Ativan) with 25-30 per cent increased risk, and high-potency opioids (including hydromorphone, codeine and morphine), which increased the risk of collisions by 24 per cent.

Brubacher said that while those findings are noteworthy, they should be kept in perspective. He said consuming alcohol while driving — even at the legal limit — is much riskier.

"Here [with medications] we found a 25-30 per cent increased risk, which sounds like a lot, but if you're driving just at the legal limit, your risk is doubled, so that would be 100 per cent increased risk," he said.

Brubacher said there were takeaways from this work for prescribers, including that reducing prescriptions of some of the higher risk drugs generally makes driving safer. He said if counselling or other treatment could work, that's worth considering before turning to medications.

For people using these medications, Brubacher just suggests being aware of the increased risk, noting that tolerance to drugs doesn't appear to reduce it. He said combining any of the higher risk medications with alcohol is a bad idea.

But he said the amount of risk the research shows isn't grounds for banning driving while on certain prescriptions.

"I think my message is more about managing the risk than avoiding it all together," said Brubacher.

To hear Jeff Brubacher's interview on All Points West, click here: