# Prevalence and Temporal Trends of Mental Disorders in Persons with Opioid Use Disorder and Concurrent Mental Disorders in British Columbia, Canada, Using Population-Level Administrative Data, 2013 to 2021: Prévalence et tendances temporelles des troubles mentaux chez les personnes souffrant d’un trouble lié à la consommation d’opioïdes et de troubles mentaux concomitants en Colombie-Britannique, au Canada, à partir de données administratives au niveau de la population, entre 2013 et 2021

## TL;DR

This study shows that mental disorders are common among people with opioid use disorder in British Columbia, and their rates have increased significantly from 2013 to 2021.

## Contribution

The study provides the first population-level analysis of mental disorder prevalence and trends among individuals with opioid use disorder in British Columbia.

## Key findings

- Anxiety disorders were the most common mental disorder among individuals with opioid use disorder (91.7%).
- The annual period prevalence of any mental disorder increased by 7.0% per year from 2013 to 2021.
- Males had a higher annual age-standardized prevalence of mental disorders compared to females.

## Abstract

Opioid use is a major public health issue and associated with a broad range of comorbid mental disorders. Globally, there is considerable variability in reported rates of mental disorders among individuals with opioid use disorder (OUD), limiting timely intervention and evidence-based treatment among this population. We estimate the prevalence of specific mental disorders among individuals with a concurrent OUD using population-level administrative data in British Columbia, Canada.

A population-based retrospective observational study using individual-level linked health administrative data in British Columbia, Canada. Individuals with an OUD and concurrent mental disorder between January 1, 2013, and August 31, 2021, were included and followed from their first indication of OUD until censoring (death, administrative loss to follow-up, or August 31, 2021). We reported annual period (2013-2021) prevalence rates and age-standardized prevalence rates per 100,000 population (stratified by sex).

The population included 73,855 individuals (female 40.6%, median age, 36 [27-48]) with an OUD and concurrent mental disorder. During the observation period anxiety disorders were the most prevalent (91.7%) mental disorders followed by depression (73.6%), bipolar disorder (35.3%), schizophrenia spectrum disorders (20.4%), and personality disorders (19.5%). Among the population, the annual period prevalence of any mental disorder increased from 35,603 in 2013 to 60,940 in 2021, with an average annual percent difference of 7.0%, driven by increases in schizophrenia spectrum disorders and attention deficit/hyperactivity disorder. Overall, the annual age-standardized prevalence of any mental disorder was higher among males.

Our findings demonstrate a steadily growing prevalence of people with OUD and a concurrent mental disorder and emphasize the need for access to mental disorder treatment among this population. Estimating specific mental disorder prevalence is a pragmatic step toward informing clinical guidelines, service needs, and health system planning.