Driving while on prescription opioids has played an increasingly significant role in fatal motor vehicle crashes, irrespective of alcohol use and demographic characteristics, according to a new study conducted at the Columbia University Mailman School of Public Health. The findings are published online in JAMA Network Open.

“There has been heightened concern about drugged driving in recent years due in part to increasing permissibility and availability of marijuana and excess consumption of prescription opioids,” said Guohua Li, MD, DrPH, professor of Epidemiology at the Columbia Mailman School. “However, few epidemiological studies have assessed the causal role of prescription opioids in fatal motor vehicle crashes.”

The researchers studied 18,321 pairs of drivers involved in 18,321 fatal two-vehicle crashes recorded between 1993 and 2016 in the Fatality Analysis Reporting System, a dataset on all motor vehicle crashes that occurred on public roads in the US and that resulted in at least one fatality within 30 days of the crash. Each pair of drivers included an initiator whose actions or errors led to the fatal crash and a non-initiator involved in the same crash.

“This pair-matched analysis provides compelling evidence that use of prescription opioids by drivers is a significant contributing factor for fatal two-vehicle crashes,” noted Li, who is also the founding director of the Center for Injury Epidemiology and Prevention at Columbia.

The most common driving error leading to fatal two-vehicle crashes was a failure to keep in lane (41%), followed by failure to yield right of way (25%), and speeding (17%). Failure to keep in lane accounted for the majority (55%) of errors made by drivers who tested positive for prescription opioids. Reduced alertness and lane tracking ability are among the side effects of prescription opioids.

The prevalence of prescription opioids detected for the years studied increased from 2.0% to 7.0% among crash initiators, and from 0.9% to 4.6% among non-initiators. Crash initiators were also more likely to test positive for alcohol (29%) than non-initiators (10%).

“After adjusting for demographic characteristics and driving history, we found that use of prescription opioids more than doubles the risk of fatal two-vehicle crash initiation, regardless of the blood alcohol level,” said Stanford Chihuri, co-author of the study. “It is important that clinicians take into consideration these medications’ adverse effect on driving safety when counseling patients about the risks of opioids.”