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Prescribed opioid doses are excessive in Ontario – thousands at risk: study


A new study led by researchers at the Institute for Clinical Evaluative Sciences (ICES) and St. Michael’s Hospital has found that Ontarians who were treated with high doses of opioids were almost three times more likely to die of opioid-related causes compared to those prescribed lower doses. The study found that even moderate opioid doses increase the risk of dying. Opioids include strong painkillers like morphine, codeine and oxycodone.

“These drugs are of great value if prescribed carefully for patients who are selected appropriately. However, they are being prescribed widely to large numbers of people in doses that can be very dangerous. Many people do not appreciate that these drugs can cause death, particularly at high doses or when taken with alcohol or other sedating drugs, as they often are,” says lead author Tara Gomes, an epidemiologist at ICES.

The study examined prescriptions paid by Ontario’s public drug plan for patients aged 15 to 64 during the 9-year period from 1997 to 2006 and found that:

  • 1,463 ODB-eligible Ontarians treated with opioids died of opioid-related causes, which equates to an average of 13 opioid-related deaths per month in this population
  • Patients treated with opioids who died of opioid-related causes were more likely to have a history of alcoholism, to have been treated with benzodiazepines and other sedatives, and to have obtained opioids from multiple physicians and pharmacies
  • Opioid doses exceeding thresholds described in Canadian guidelines (200 mg morphine per day, or equivalent) are associated with an almost 3 times higher risk of opioid-related mortality compared with those prescribed low doses.
  • Even moderate doses of opioids (equivalent to between 50 and 199 mg of morphine daily) were associated with a doubled risk of opioid-related mortality
  • The importance of these findings is underscored by our previous research which found that in recent years over 400 Ontarians have died of opioid related causes annually, and thousands of Ontarians are being treated with long-acting opioids at doses in excess of those recommended by clinical guidelines

“What this study makes clear is that treatment with opioids, even at seemingly modest doses, can cost patients their lives,” says Dr. David Juurlink, a co-author on the study and ICES scientist. “The long-term use of opioids for chronic non-cancer pain is not supported by good evidence. Safer treatments are available, but opioid prescribing keeps increasing year after year. And each year, the addictions mount and the deaths pile up. This is the single most important drug safety problem facing us today.”

The study “Opioid dose and drug-related mortality in patients with nonmalignant pain,” is in the April 11, 2011 issue of Archives of Internal Medicine.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.

St. Michael’s Hospital provides compassionate care to all who walk through its doors. The Hospital also provides outstanding medical education to future healthcare professionals in more than 23 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, and care of the homeless are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing Knowledge Institute, research at St. Michael’s Hospital is recognized and put into practice around the world. Founded in 1892, the Hospital is fully affiliated with the University of Toronto. For more information, please contact:

For Tara Gomes or Dr. David Juurlink

For Dr. Muhammad Mamdani or Irfan Dhalla

  • Julie Saccone
  • Senior Public Relations Specialist
  • St. Michael's Hospital
  • 416-864-5047
  • [email protected]

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