Chronic 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.

To assess the association between long term prescription opioid treatment medically dispensed for non-cancer pain and the initiation of injection drug use (IDU) among individuals without a history of substance use, Canadian investigators evaluated a retrospective cohort of almost 60,000 patients without cancer but with periods of chronic prescription opioid use between 2000 and 2015.

These patients were matched to patients with periods of episodic use, acute use, or no use during the same interval. After adjustment, initiation of injection drug use was 8 times more common among patients with chronic opioid use than among those with no use. Such initiation was more frequent among younger patients and those using higher opioid doses.

The authors of the research published in the Brititsh Medical Journal caution that chronic prescription opioids should not be involuntarily tapered or discontinued. Clinicians should be alert to initiation of injection drug use among chronic opioid users, particularly those who are younger or using higher opioid doses.