The risk of long-term opioid use among immigrants: a national registry-linkage study.

Aims: We aimed to investigate the association between being an immigrant and long-term prescription opioid use in Norway in 2010-2019.

Methods: Nested case-control study. The cases were all persons 18 years of age or older with long-term opioid use - that is, the use of prescription opioids longer than 3 months (=215,642).