Opioid volume drops in Ontario, but many still exceed recommended dose: report

Prescription pill bottle containing oxycodone and acetaminophen are shown on June 20, 2012. (Graeme Roy / THE CANADIAN PRESS)

TORONTO - Ontario doctors appear to be prescribing lower amounts of opioids overall to treat patients with pain, say researchers, but many longtime users continue to be given daily doses of the potent narcotics that exceed national practice guidelines.

A report by the Ontario Drug Policy Research Network found the number of people prescribed an opioid remained relatively constant over the past five years, with 1.95 million, or one in seven Ontarians, treated with the potentially addictive medications last year.

However, the overall volume of opioids dispensed fell by 18 per cent between January 2015 and March 2017, driven by a reduction in the amount of long-acting, slow-release formulations - such as fentanyl patches and some types of oxycodone - prescribed to patients.

"There might be a good news story here, in that while there's similar numbers of people being treated with opioids for pain, it seems as if they're getting less opioid and they're getting those opioids in more prescriptions," said lead author Tara Gomes, a scientist at St. Michael's Hospital in Toronto and the Institute for Clinical Evaluative Sciences.

"That aligns really well with some of the recommendations that have been coming out of guidelines that suggest physicians try and lower doses but also have people get dispensed smaller amounts of opioids at a time," she said.

"Because that leads to less leftover pills in people's cabinets, perhaps people not using the drugs for quite so long, so they might not become dependent on them, which can lead to addiction issues."

Still, researchers found that nearly 40 per cent of long-acting opioid prescriptions dispensed to people already using the drugs for pain had daily doses that surpassed the recommended threshold under 2017 Canadian prescription guidelines for opioid use in chronic non-cancer pain.

A panel of experts who penned the guidelines said opioids like oxycodone, hydromorphone and the fentanyl patch should be prescribed at a daily dose of less than the equivalent of 90 milligrams of morphine, and ideally less than 50 mg.

Gomes said the number of patients exceeding that dose as suggested by prescription data is likely even higher because long-term opioid users often are treated with both long-acting and immediate-release opioids.

In 2016, the report found almost 12 per cent of Ontarians were prescribed an opioid for all types of pain; 2.3 per cent for mostly seasonal cough suppression; and 0.4 per cent for opioid addiction.

Although 0.4 per cent may seem like an insignificant number, Gomes said that figure represents one in every 243 people in the province getting help for an opioid addiction - and that only accounts for those who have sought treatment.

While opioids to treat pain are being prescribed relatively evenly across all income groups in the province, the use of replacement drugs like methadone and suboxone were disproportionately concentrated among lower socio-economic populations.

"In our last work, we've also seen that these lower-income groups are also more likely to die of opioid-related causes," said Gomes, suggesting that less affluent people may be more vulnerable to the negative consequences of opioid use.

Dr. Jason Busse, co-chair of the group that wrote the national prescribing guidelines, said it's interesting to see that the total opioid volume has fallen by 18 per cent over the last two years.

"It does suggest that there have been changes in how prescribers are approaching the use of opioids and it does appear that those trends are going down," said Busse, a researcher in the National Pain Centre at McMaster University, who was not involved in the report.

"So that certainly seems encouraging."

He said it's not surprising that about 40 per cent of long-acting opioid prescriptions for longtime users exceed the recommendations in the guidelines, which were just released in May. Previous guidelines from 2010 set the upper recommended limit for patients with chronic non-cancer pain at a morphine equivalent of 200 mg per day.

"These would be the legacy patients, individuals that have been using opioids for a number of years in some case, perhaps even decades," Busse said from Hamilton, noting that such patients are advised to try to slowly taper their use to the lowest possible effective dose, potentially including discontinuation.

"But we know there are risks to decreasing of the dose, including opioid withdrawal. Everybody involved in long-term opioid therapy will become physically dependent."

Gomes said researchers also found geographical variations in opioid prescribing, with people dispensed an opioid to treat pain or addictions concentrated more in northwestern and rural regions of Ontario.

The North Bay Parry Sound District Health Unit and Haliburton, Kawartha, Pine Ridge District Health Unit had the highest proportions of residents receiving opioids for pain, at 17.4 per cent of the population.

The Thunder Bay District Health Unit had the highest proportion of its population prescribed either methadone or suboxone to treat addiction, at 2.2 per cent - or about one in every 50 residents - while in Northwestern Ontario, 1.4 per cent of residents received the replacement opioids.

"I think that also drives home the fact that this has become such an issue that people have become addicted to these drugs," said Gomes. "It's impacting a large proportion of people across Ontario and even more so in certain areas of the province."