Preadmission Opioid Use and 1‐Year Mortality Following Incident Myocardial Infarction: A Danish Population‐Based Cohort Study (1997–2016)

BACKGROUND: Opioid use has been linked to an increased risk of myocardial infarction and cardiovascular mortality, but the prognostic impact of opioid use before an incident myocardial infarction is largely unknown. METHODS AND RESULTS: We conducted a nationwide population‐based cohort study including all patients hospitalized for an incident myocardial infarction in Denmark (1997–2016). Based on their last redeemed opioid prescription before admission, patients were categorized as current users (0–30 days), recent users (31–365 days), former users (>365 days), and nonusers. One‐year all‐cause mortality was calculated using the Kaplan–Meier method. Hazard ratios (HRs) were computed using Cox proportional hazards regression analyses, adjusting for age, sex, comorbidity, any preceding surgery within 6 months before the myocardial infarction admission, and medication use before the myocardial infarction admission. We identified 162 861 patients with an incident myocardial infarction. Of these, 8% were current opioid users, 10% were recent opioid users, 24% were former opioid users, and 58% were nonusers of opioids. One‐year mortality was highest among current users (42.5% [95% CI, 41.7%–43.3%]) and lowest among nonusers (20.5% [95% CI, 20.2%–20.7%]). Compared with nonusers, current users had an elevated 1‐year all‐cause mortality risk (adjusted HR, 1.26 [95% CI, 1.22–1.30]). Following adjustment, neither recent users nor former users of opioids were at elevated risk. CONCLUSIONS: Preadmission opioid use was associated with an increased 1‐year all‐cause mortality risk following an incident myocardial infarction. Opioid users thus represent a high‐risk subgroup of patients with myocardial infarction.