Factors Associated With Opiate Use Among Psychiatric Inpatients: A Population-Based Study of Hospital Admissions in Ontario, Canada

Background: Use of opiates, including synthetic opioids, is associated with a number of negative consequences, including increased risk of opioid use disorders and other mental health conditions. However, studies are limited in examining patterns of opiate use among persons in inpatient psychiatry, particularly those that consider the relationship between pain and opiate use. Objective: This study examined the prevalence in the prior 12 months to admission and patterns of opiate use and pain in a population-based study of persons admitted to inpatient psychiatry in Ontario, Canada. Methods: We conducted retrospective cross-sectional study of 165 434 persons admitted to inpatient psychiatry between January 1, 2006 and December 31, 2017. Using data from the Resident Assessment Instrument for Mental Health, we examined prevalence and factors associated with opiate use in the prior 12 months by a number of patient characteristics, including demographics, mental and physical health status, concurrent substance use, pain severity and frequency, and health region of residence. Results: The prevalence of opiate use within 12 months of admission was 7.5%, between 17% and 22% among those experiencing daily pain, and 27% among persons with a primary substance use disorder. Multivariable analyses revealed strong associations among demographic and clinical variables with opiate use (c = 0.91), including being of younger age, use of other substances, greater frequency and severity of pain, and health region of residence. Conclusion: The strong relationship between pain and opiate use in this population, and the regional variation in this pattern, supports the need for integrated care for mental illness and substance use, and therapeutic approaches to pain management that reduce risks of problems associated with substance use for persons with mental health conditions.