Comorbidities in an Australian sample of chronic and new opioid users

Introduction and aims: Mental health disorders and substance abuse are risk factors that both precede and follow chronic opioid use. We predicted that incident opioid users would have lower rates of mental health comorbidities than chronic opioid users, but that incident chronic opioid users would have lower rates of mental health comorbidities than prevalent chronic users.Design and methods: We used administrative health claims data to evaluate differences in lifetime mental health and substance abuse comorbidity profiles of people who were prevalent and incident chronic opioid users, as well as those who used opioids acutely. Results were stratified by age.Results: Over 5,188 people were prevalent chronic opioid users at study entry. Of the 10,079 people who initiated opioids, 10.2 percent had a subsequent chronic episode (incident chronic) and the remainder stopped within 90 days (incident acute). In prevalent chronic users compared to incident chronic users, rates of depression and anxiety were higher across all age groups (odds ratio (OR) across age groups range from = 1.60, 95 percent confidence interval (CI) = 1.35,1.89, to OR = 6.66, 95 percent CI = 3.02, 14.69) and prevalence of alcohol abuse was higher in those aged 55 to 74 years (OR = 5.11, 95 percent CI = 1.83, 14.24, p = 0.002). Acute users were less likely than incident chronic users to have depression and anxiety in those aged over 74 years (depression OR = 0.82, 95 percent CI = 0.70, 0.95; anxiety OR = 0.82, 95% CI 0.70, 0.98).Conclusions: Mental health morbidities commonly associated with chronic opioid use increase in prevalence as chronic use continues. Refereed/Peer-reviewed