Chronic Prescription Opioid Users Are at Excess Risk for Initiating Injection Drug Use

The opioid epidemic is driven largely by use or misuse of prescription oral opioids, but injection drug use also has increased in recent years. Qualitative studies suggest that injection drug use in prescription opioid users might be precipitated by events such as developing tolerance or interrupted access to medications.

Canadian investigators evaluated a retrospective cohort of almost 60,000 patients (age range, 11–65) without cancer but with periods of chronic prescription opioid use (≥90 days, with medication supply for ≥50% of days) between 2000 and 2015. These patients were matched to patients with periods of episodic use (≥90 days, but <50% medication supply), acute use (<90 days), or no use during the same interval. Injection drug us…