While Maryland is facing a growing epidemic of opioid addiction, there has not been a corresponding increase in traffic fatalities involving drivers who have the drug in their systems, a new report examining data from the state medical examiner found.

“The fact that opioid crashes in Maryland over the last 10 years have been more or less steady was a surprise,” said Johnathon P. Ehsani,one of the report’s authors. “That is striking, because Maryland is one of those states that has been quite severely affected by the overall opioid epidemic.”

The study was carried out by the state medical examiner in Baltimore in concert with researchers from the Johns Hopkins Bloomberg School of Public Health, where Ehsani is a professor, and the University of Buffalo.

Figuring out the drivers who had opioids in their systems before a crash was complicated by a simple fact: emergency crews often administer opioids — including the powerful painkiller fentanyl — to those who have been injured. As a result, autopsies detect opioids in the systems of those who have died of their injuries.

To filter out those cases, researchers focused on a subsample of drivers who died at the scene.

“In such cases, the likelihood of pain management is likely to be considerably lower than those who died hours or days following the crash,” the report said.

The United States recorded more than 70,000 drug overdose deaths in 2017, and opioid overdoses were nearly 68 percent of those. The federal Centers for Disease Control singled out 23 states, including Maryland, that had statistically significant increases that year.

“Our study is a single data point in a national phenomenon that we’re looking at,” Ehsani said when asked why overall opioid deaths are up in the state, but opioid-involved crashes have not increased significantly.

“It could be a number of things — and all of them are coulds,” he said. “It could be that a number of people who are impaired by opioids choose not to drive. It could be that there is some self-selection going on in that population or it could be that some of those who are most seriously impaired are unable to or don’t have access to a vehicle to drive.”

The report found that the average person killed in an opioid-related crash in Maryland is white, male and between the ages of 50 and 55. Women, African Americans, Latinos and Asians are far less likely to be involved in such crashes. The report also determined that people in rural counties — notably on Maryland’s Eastern Shore — also were more likely to die in opioid-involved crashes.

Ehsani said that earlier national studies suggested that the number of opioid-related crashes was increasing.

“We applied a stricter definition than our other colleagues did,” he said. “We were more conservative in our case definition. But my caution is to say that the jury is still out. We need to keep looking at this question and analyzing the data, and see truly in Maryland whether things are stable, and even if they are, how can we keep them that way?”

“Until now, we knew little about the extent of the crash risk that opioid addiction, abuse or impairment impose on traffic safety in Maryland,” said John B. Townsend II, a spokesman for AAA., who cited both the study and earlier research by the AAA Foundation for Traffic Safety. “An overwhelming majority of drivers — 90.8 percent — perceive people driving about using illegal drugs to be a very serious or somewhat serious threat to their personal safety.”

In a report in October, the AAA foundation lamented the fact that when a drug is prescribed or bought over the counter, users may not know whether it is appropriate for use while driving.

“While not all prescription and OTC drugs are impairing, drivers may not possess the knowledge necessary to distinguish between impairing and non-impairing medications or the interactions of various medications,” the report said.

It continued: “Health care professionals, law enforcement officers, judicial personnel, and others closely involved with drivers are instrumental in preventing prescription and OTC drug-impaired driving. However, they too may be unaware of the severity of the problem and may lack the resources to address it.”

The foundation’s report echoed Ehsani’s thoughts about why white males in the 50-54 age range might be more prone to opioid crashes than those of other ages.

“It would be reflective of the background use in the general population,” he said. “There is some literature to suggest that physicians are more likely to prescribe opioids to older adults, who generally have pain.”

That was reflected in the AAA report: “While the risk for [over the counter] and prescription drug-impaired driving exists across the population, this concern is particularly salient for older drivers.”