Study: Prescription Drug Databases Overestimate Opioid Misuse

By Pat Anson, PNN Editor

Prescription drug monitoring has long been seen as the gold standard for tracking the opioid crisis. Patients who fill an opioid prescription for more than three months are considered long-term users with a higher risk of misuse, addiction and overdose. Many pharmacy chains assign a “risk score” to these patients and their doctors could even get a warning letter from the government.

But in a small study of emergency room patients, Canadian researchers found the risk of opioid misuse by long-term users is small and one out of five patients who fill opioid prescriptions don’t even use them. Their findings suggest that prescription databases alone are a poor way to measure opioid misuse.

“The rate of long‐term opioid use reported by filled prescription database studies should not be used as a surrogate for opioid misuse,” said lead author Raoul Daoust, MD, a professor and researcher in the Department of Family Medicine and Emergency Medicine at the University of Montreal.

Daoust and his colleagues surveyed 524 patients who were discharged from a hospital emergency department (ED) with an opioid prescription for acute pain. Instead of just relying on a database to track their prescriptions, the researchers asked the patients about their opioid use.

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Three months after discharge, only 47 patients – about 9 percent – said they were still using opioids. Of those, 72% said they used opioids to treat their initial pain and 19% were using the drugs to treat a new pain condition.

The remaining four patients said they used opioids for another reason, suggesting possible misuse. That’s less than one percent (0.8%) of the original 524 patients.

“Within the limit of our study, our results suggest that the risk of long‐term opioid use for reasons other than pain is low for ED discharged patients with an opioid prescription treating an acute pain condition,” Daoust reported in the journal Academic Emergency Medicine.

Daoust’s findings are controversial because they throw into question the widely accepted theory that all opioid prescribing is risky, whether it’s for chronic or acute pain. The methodology used in his study was questioned by one critic.

"Emergency physicians should not be reassured by the authors' findings. The lack of a denominator, poor response rate (56%), and applied definition of misuse are significant limitations,” said Gail D'Onofrio, MD, a professor of emergency medicine and chair in the department of emergency medicine at Yale University.

D'Onofrio cites a 2017 CDC study, which found that the probability of long-term opioid use increases sharply after the first few days of treatment.

“Transitions from acute to long-term therapy can begin to occur quickly: the chances of chronic use begin to increase after the third day supplied and rise rapidly thereafter,” CDC researchers warned.

But that analysis is based solely on the number of opioid prescriptions – not actual opioid use. And Daoust found that studies like that are a poor way to measure risk.

“These studies used filled prescriptions databases that could overestimate opioid use since not all patients filling an opioid prescription consumed them. As a case in point, in this study, 21% of patients who filled their opioid prescription after the initial ED visit did not consume them,” Daoust reported.

What is the risk of long-term opioid use after an emergency room visit? In a large 2017 study by the Mayo Clinic, only about 1 percent of ER patients given an opioid prescription progressed to long term use – similar to what Daoust found.

"Our paper lays to rest the notion that emergency physicians are handing out opioids like candy," said lead author Molly Moore Jeffery, PhD, scientific director of the Mayo Clinic Division of Emergency Medicine Research. “Most opioid prescriptions written in the emergency department are for shorter duration, written for lower daily doses and less likely to be for long-acting formulations."

A 2018 study also questioned the value of prescription drug monitoring programs (PDMPs) which have long been promoted as critical tools in the fight against opioid abuse. The study found little evidence that PDMPs are reducing overdoses and that they may lead to unintended consequences such as patients turning to street drugs for pain relief.