Taking a common psychoactive medication along with opioids nearly triples the chance that a patient will become a long-term opioid user, Stanford Medicine researchers have found.
Benzodiazepines -- used to relax muscles, treat insomnia and counter anxiety -- increased the chance that patients refilled their opioid prescription at least six times within a year. The class of medication includes the brand name drugs Xanax and Valium.
An article about the research was published in the Journal of General Internal Medicine.
"This investigation shows how physician behavior may influence how someone ends up being a chronic user of opioids," said John Ratliff, MD, a professor of neurosurgery and the senior author on the study.
"It's not at all unusual to use a pain medication along with a muscle relaxant," Ratliff said, adding that he has prescribed both medications to patients in the past, but no longer.
Ratliff and his fellow researchers looked at the medical records of nearly 2.5 million patients who went to their doctors complaining of lower back or leg pain. They excluded the patients who appeared to have a serious problem, such as cancer or an infection, as well as patients who had taken opioids in the six months before the diagnosis.
Most of the patients they were looking at, said Ratliff, "are people who have thrown their back out."
Ratliff said that while some patients who were more likely to use opioids long term may have convinced their physicians to write benzodiazepine prescriptions, he didn't believe that was behind most of the long-term opioid use. Both the patients who were using benzodiazepines before they were prescribed opioids and those who received prescriptions afterward showed an increased tendency to use opioids long term, he noted. Also, none of the patients were using opioids before their first doctor visit.
"We're not sure why they're more likely to become long-term opioid users," Ratliff said. "Perhaps there's something with the interaction."
The researchers found that from 2008 to 2015, the percentage of patients receiving an opioid prescription for their pain during the initial doctor visit dropped from about 35% to 27%. While the drop was encouraging, the researchers failed to find a corresponding drop in benzodiazepine prescribing -- it remained close to 11%.
In fact, they found that about 18% of the patients received prescriptions for both drugs at some point in the year following their first visit to a physician for their leg and back pain.
The co-prescribing is troubling not only because it appears to lead to long-term opioid use, but also because taking the drugs together increases the chance of overdose. Both classes of medications suppress the central nervous and respiratory systems.
Ratliff said he plans to look into why the two medications prescribed together lead to long-term opioid use. "That's the next step," he said.
Photo by Toa Heftiba