STUDY HYPOTHESIS: Use of opioids for treatment of headache in the emergency department (ED) is associated with an increased 1-year risk of opioid-related adverse events. OBJECTIVE: To assess the safety and efficacy of opioid prescribing for ED patients with headache. METHODS: We performed a multicenter observational cohort study using linked administrative data. All patients discharged from an ED in the province of Alberta, Canada with a headache diagnosis between 2010 and 2020 were included. Opioid-treated patients filled opioid prescriptions within 72 h of their ED visit, and were matched to untreated controls using propensity scores. The 1-year primary outcome was a composite of long-term prescription opioid use (LTU), opioid-related ED visit or hospitalization, or new opioid agonist therapy (OAT). Secondary outcomes included all-cause acute care utilization and 7-day ED return headache visits. RESULTS: Of 323,932 eligible headache visits, 5.7 % received opioids. Opioid-treated patients were comparable to controls on all baseline characteristics. The primary outcome occurred in 8.7 % of opioid-treated patients and 5.8 % of controls (aOR 1.65 [1.49-1.82]
NNH = 29). Opioid-treated patients had higher rates of LTU (7.7 % vs. 4.8 %), all-cause ED visit (20.8 % vs. 19.0 %), all-cause hospitalization (16.7 % vs. 14.8 %), and 7-day revisit (aOR = 1.61 [1.49-1.74]
NNH = 21) but did not experience more opioid-related ED visits or hospitalizations, or new OAT. Opioid prescription potency and duration were strong predictors of harm. CONCLUSION: Opioid prescriptions are associated with ED revisits, hospitalizations and LTU in headache patients, without improved efficacy. These findings support the growing notion that opioids are not indicated for ED headache management.