Nearly a quarter (23.9 per cent) of initial opioid prescriptions in Ontario had a daily dose of more than 50 milligram morphine equivalents (MME), exceeding the suggested dose threshold for opioid prescriptions outlined in North American clinical guidelines, according to a new study from the Institute for Clinical Evaluative Sciences (ICES) and St. Michael's Hospital.
"The U.S. and Canadian clinical guidelines for prescribing opioids for chronic non-cancer pain suggest that doctors should avoid initiating opioids at daily doses above 50 MME. Our study found that nearly one-quarter of Ontarians taking an opioid for the first time received a daily dose exceeding this threshold, and for certain indications such as knee, hip and shoulder surgeries and Caesarean sections, the dose was even higher," says Dr. Tara Gomes, lead author of the study and a scientist at ICES.
The study, published today in the journal Pain, examined initial opioid prescriptions for more than 650,000 Ontarians from April 2015 to March 2016 and linked each to health administrative data from Ontario's publicly funded health care system.
"Due to concerns about the overprescription of opioids, there is an ongoing need to determine how to resource alternative non-pharmaceutical pain management strategies . In order to do this, we wanted to get a clear picture of the clinical indications associated with opioid initiation and the characteristics of those initial prescriptions," adds Gomes, who is also a scientist at the Li Ka Shing Knowledge Institute of St. Michael's Hospital.
Prescriptions for opioids have increased sharply in the last decade, making Canada the second highest per-capita user of opioids in the world. Furthermore, 1 in 8 Ontarians was dispensed an opioid in 2016, and Ontario has seen a four-fold increase in overdose deaths in the last 25 years, according to earlier research by Gomes.
The researchers grouped the reasons for starting opioids into six clusters: dental pain (23.2 per cent of prescriptions), postsurgical pain (17.4 per cent), musculoskeletal pain (12.0 per cent), trauma-related pain (11.2 per cent), cancer or palliative care (6.5 per cent), and other types of pain (17.7 per cent). Overall, 78,481 (12.0 per cent) of individuals could not be linked to any of the six indications).
The study showed that the dose and duration of initial opioid prescriptions varied considerably by indication. Dental pain accounted for nearly one in four new opioid prescriptions, but these were generally of short duration and low dose. In contrast, one in six new opioid prescriptions were for postsurgical pain, and these patients generally started on higher daily doses (over 40 per cent of them were prescribed more than 50 MME, and for hip and knee surgery at least 25 per cent were prescribed 90 MME or more).
"We know that patients' first opioid prescriptions are critically important. Across all clinical indications, a high percentage of people received daily doses of more than 50MME and prescription lengths exceeding seven days, a combination which has been associated with opioid-related adverse events and long-term opioid use. Given this, we need to think about alternative pain management options. This data can help us understand the types of services—like physiotherapy and cognitive behavioural therapy—that might be appropriate to help avoid our reliance on opioids for some indications," says Gomes.
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"Clinical indications associated with opioid initiation for pain management in Ontario, Canada: A population-based cohort study," was published in the current issue of Pain.