RT Journal Article SR Electronic T1 Relation between opioid-related harms and socioeconomic inequalities in Ontario: a population-based descriptive study JF CMAJ Open JO CMAJ FD Canadian Medical Association SP E478 OP E485 DO 10.9778/cmajo.20180084 VO 6 IS 4 A1 Zoe F. Cairncross A1 Jeremy Herring A1 Trevor van Ingen A1 Brendan T. Smith A1 Pamela Leece A1 Brian Schwartz A1 Karin Hohenadel YR 2018 UL http://www.cmajopen.ca/content/6/4/E478.abstract AB Background: Negative health outcomes associated with the use of both prescribed and nonprescribed opioids are increasingly prevalent. We examined long-term trends in opioid-related harms in Ontario across a set of 6 indicators and the relation between harms and neighbourhood income in 2016.Methods: We examined rates of neonatal abstinence syndrome, opioid poisoning (fatal and nonfatal) and nonpoisoning opioid-related events from 2003 to 2016 in Ontario using population-based health administrative databases. We conducted descriptive analyses for harm indicators across neighbourhood income quintiles in 2016 (2015 for death). We examined social inequalities in opioid-related harms on both relative (prevalence ratio) and absolute (potential rate reduction) scales.Results: Rates of opioid-related harms increased dramatically between 2003 and 2016. In 2016, neonatal abstinence syndrome and opioid poisoning and nonpoisoning events showed a strong social gradient, with harm rates being lowest in higher-income neighbourhoods and highest in lower-income neighbourhoods. Prevalence ratios for the lowest-income neighbourhoods compared to the highest-income neighbourhoods ranged from 2.36 (95% confidence interval [CI] 2.15–2.58) for emergency department visits for opioid poisoning to 3.70 (95% CI 2.62–5.23) for neonatal abstinence syndrome. Potential rate reductions for opioid-related harms ranged from 34.8% (95% CI 29.1–40.1) to 49.9% (95% CI 36.7–60.5), which suggests that at least one-third of all harmful events could be prevented if all neighbourhoods had the same socioeconomic profile as the highest-income neighbourhoods.Interpretation: Rates of opioid-related harms increased in Ontario between 2003 and 2016, and people in lower-income neighbourhoods experienced substantially higher rates of opioid-related harms than those in higher-income neighbourhoods. This finding can inform planning for opioid-related public health interventions with consideration of health equity.