Opioid-related mortality associated with daily dose for nonmalignant pain

A daily dose of opioids for nonmalignant pain is strongly associated with opioid-related mortality, and doses of 200 mg or more of morphine or equivalent are associated with a particularly high risk, according to a recent study published in Archives of Internal Medicine.

To characterize the relationship between opioid dose and opioid-related mortality, investigators looked at a cohort of Ontario, Canada, residents aged 15 to 64 years who were eligible for publicly funded prescription drug coverage, had received at least 1 prescription for an opioid from August 1, 1997, through December 31, 2006, for nonmalignant pain, and for whom an opioid-related cause was the reason for death as determined by the coroner. Cases and potential controls were excluded if they had been diagnosed with cancer or had received palliative care services in the 6 months prior to their index date.

Over the study period, investigators identified 498 eligible patients whose deaths were related to opioids and 1,714 matched controls. After extensive multivariable adjustment, the study showed that an average daily dose of 200 mg or more of morphine (or equivalent) was associated with a nearly 3-fold increase in the risk of opioid-related mortality (OR=2.88; 95% CI, 1.79–4.63) compared with patients receiving <20 mg/d.

“The importance of this finding is underscored by the fact that doses in this range are common. In 2008, 27% of Ontario social assistance recipients who were treated with long-acting opioids received daily doses exceeding this threshold,” the authors wrote.