Background
Opioids are essential medicines for pain management; however, long-term use is associated with negative outcomes, including addiction. The aim of the study was to analyze the risk of long-term use after an initial opioid prescription and examine associated sociodemographic and health care-related risk factors.

Methods
We identified a strictly defined, five-year opioid-naïve population of adults aged 18–64 years who received an initial opioid prescription between 2016 and 2020 in Swedish national registers. We modeled the association between individual characteristics and odds of long-term ( > 3 months) versus short-term ( ≤ 3 months) use, and odds of different durations of use ( > 3–6, >6–12, and >12 months) using logistic regression analyses.

Results
Of 754,982 opioid-naïve individuals with an initial opioid prescription, 8.1% use opioids long-term. Individuals treated for a recent external injury have lower odds of long-term opioid use (e.g., >12 vs ≤3 months: OR 0.55, 95% CI 0.52–0.59), whereas those who initiated treatment in primary care have higher odds (e.g., >12 vs ≤3 months: OR 3.02, 95% CI 2.90–3.14). Individuals with a history of substance use disorders and greater use of psycholeptic drugs have higher odds of long-term use. Sociodemographic factors, including older age, lower education level, and not cohabiting are also associated with longer durations of use.

Conclusions
Of opioid-naïve individuals, 8.1% develop long-term prescription opioid use, with higher odds among individuals with psychiatric history and whose opioid treatment initiated in primary care. Careful evaluation of patient health and regular follow-up are essential to reduce the risk of long-term opioid use.