Non-medical prescription opioid use, prescription opioid-related harms and public health in Canada: an update 5 years later.

Five years ago, we highlighted Canada's emerging problem of prescription opioid (PO)-related harms and emphasized the need for targeted surveillance, research and interventions. Overall levels of PO use in the Canadian population have grown by 70% since then, while at the same time levels of non-medical PO use (NMPOU) in general and in key risk populations have continued to be high; furthermore, PO-related harms - specifically morbidity (e.g., treatment admissions) and mortality (e.g., overdose deaths) - have risen substantively. Unfortunately, major knowledge gaps related to systematic monitoring of PO-related harms continue to exist; for example, no national morbidity or mortality statistics are available. Investigator-driven research has generated important insights into the epidemiology and impacts of PO-related harms: high correlations between population-level PO dispensing and/or PO dosing and harms; high rates of co-occurrence of NMPOU and co-morbidities; and distinct NMPOU-related risk dynamics among street drug users. Select policy measures have been implemented only recently at the federal and provincial levels; these interventions remain to be systematically evaluated, especially given preliminary indications of reductions in PO-related harms (e.g., NMPOU) unfolding prior to the interventions. For these purposes, improvements in surveillance tools and research resources devoted to the extensive public health problem of PO-related harms in Canada continue to be urgently needed.