Prevalence of substance use disorder diagnoses in patients with chronic pain receiving reimbursed opioids: An epidemiological study of four Norwegian health registries.

Objectives: Since 2008, patients have had access to reimbursed analgesics, including opioids, for chronic pain in Norway. There is a need for knowledge on the occurrence and trends over time of substance use disorder (SUD) diagnoses among patients who receive reimbursed opioids for chronic pain. The primary aim of this study was to investigate the prevalence of SUD diagnoses in patients with chronic pain using reimbursed opioids from 2010 to 2019 in Norway. The secondary aim was to investigate the prevalence of other mental health diagnoses among those receiving reimbursed opioids in the subgroups with and without SUD diagnoses.

Methods: A cross-sectional design utilising data from four Norwegian nationwide registries.

Results: The annual number of individuals with SUD diagnoses increased from 377 to 932 from 2010 to 2019, while the annual prevalence of individuals with SUD remained relatively stable at around 5%. There was a higher prevalence for all categories of other mental health diagnoses among individuals with a SUD diagnosis, compared to those without a SUD diagnosis.

Conclusion: The prevalence of SUD diagnoses was low in the population using reimbursed opioids for chronic pain in Norway, but the number of patients increased in the study period because the number of individuals receiving reimbursed opioids increased. Patients with a SUD used on average twice the daily doses of opioids compared to patients without a SUD. They were also more likely to have an additional mental health diagnosis.