Opiods raise risk of road trauma
TORONTO—Taking even low doses of opioids like codeine or morphine increases the risk of being involved in a traumatic motor vehicle accident—and that risk goes up as people take higher and higher amounts of the powerful pain-killers, research suggests.
Opioids, the widely-prescribed class of drugs that also includes oxycodone, hydromorphone, and the fentanyl patch, are prescribed for both acute and chronic pain.
The study, published yesterday in JAMA Internal Medicine, found that among adult drivers prescribed opioids, a daily dose of just 20 mg of morphine (or the equivalent of another opioid) was linked to a 21 percent increased risk of road trauma.
The chance of having an accident rose to 42 percent with “high” doses of an opioid, described as 100-199 mg of morphine or its equivalent, compared to low doses of the drug.
“What we found was that the risk of a motor vehicle collision was dependent on the dose of opioid the individual was receiving,” said Dr. David Juurlink, one of the co-authors of the study by the Institute for Clinical Evaluative Sciences in Toronto.
“I think the most important observation was that even low doses of opioids—these are doses in the 20 to about 50 milligrams or so per day—were associated with an increased risk of accidents compared to very low doses,” he added.
Meanwhile, those prescribed “very high” doses of an opioid—more than 200 mg per day—also had an increased risk of road trauma while driving.
But at 23 percent, it was lower than might be expected.
Despite the high-end dose, Juurlink said the risk may be lower because patients taking that level of drug likely have been on the medication for a while and their brains have adjusted to its effects.
Another possibility is that people on very high doses drive less because they’re in severe pain, so it only appears that the risk for this group is lower, he added.
“It’s also conceivable that some people are not taking but actually selling [the drugs], so that also might attenuate the risk to a certain extent,” Juurlink reasoned.
Using Ontario prescription data and hospital records, the study looked at almost 550,000 patients aged 19-64 who received at least one publicly-funded prescription for an opioid from April, 2003 to March, 2011.
The study examined 5,300 of these patients who were treated in a hospital emergency department after being involved in a traffic accident.
While increased risk levels of 21-42 percent may seem modest at first glance, widespread prescribing of opioids means the issue of road safety is an important one, the researchers stressed.
“When you think about the hundreds of thousands, if not millions, of Canadians who take these drugs, I think it’s fair to say that the use of opioids while driving may constitute a significant and previously under-appreciated public health problem,” Juurlink warned.
Patients taking the pain-killers should consider hanging up their car keys or at least minimizing the amount they get behind the wheel, he said.
Physicians also can play a role in keeping these drivers safe, as well as their passengers, pedestrians, and other motorists with whom they interact on the road.
“I think it’s incumbent upon docs to warn patients at the time a prescription is written that they should think twice about driving,” Juurlink said.