Prevalence of Axis-1 psychiatric (with focus on depression and anxiety) disorder and symptomatology among non-medical prescription opioid users in substance use treatment: Systematic review and meta-analyses

Non-medical prescription opioid use (NMPOU) constitutes a substantial clinical and public health concern in North America. Although there is evidence of elevated rates of mental health problems among people with NMPOU, the extent of these correlations specifically in treatment samples has not been systematically assessed. A systematic review and meta-analysis were conducted for Axis-1 psychiatric diagnoses and symptoms with a principal focus on depression and anxiety disorders in substance use treatment samples reporting NMPOU at admission to treatment (both criteria within past 30 days). 11 unique studies (all from either the United States or Canada) met inclusion criteria and were included in the meta-analysis. The pooled prevalence of ‘any’ mental health problems (both diagnosis and symptoms) among substance abuse treatment patients reporting NMPOU was 43% (95% CI: 32%–54%; I² for inter-study heterogeneity: 99.5%). The pooled prevalence of depression diagnosis among substance abuse treatment patients reporting NMPOU was 27% (95% CI: 9%–45%; I²: 99.2%); the pooled prevalence of anxiety diagnosis in the sample was 29% (95% CI: 14%–44%; I²: 98.7%). The prevalence rates of psychiatric problems (both diagnosis and symptoms), depression diagnosis and anxiety diagnosis are disproportionately high in substance use treatment samples reporting NMPOU relative to general population rates. Adequate and effective clinical strategies are needed to address co-occurring NMPOU and mental health in substance use treatment systems, especially given rising treatment demand for NMPOU. Efforts are needed to better understand the temporal and causal relationships among NMPOU, mental health problems, and treatment seeking in order to improve interventions.