The 12-month prevalence of substance use and ICD-10 substance use disorders in Australian adults: findings from the National Survey of Mental Health and Well-Being

Aims. To present the prevalence of substance use and ICD-10 substance use disorders in the adult Australian population using data from the National Survey of Mental Health and Well-Being (NSMHWB). Design. A cross-sectional survey assessing substance use and ICD substance use disorders (harmful use and dependence). Setting and participants. A household survey of a nationally representative sample of 10 641 Australian adults (aged 18 years or older). Measurements. Trained survey interviewers administered a structured interview based on the Composite International Diagnostic Interview (CIDI). Findings. In the past 12 months 6.5% of the sample had an ICD-IO alcohol use disorder (95% CI: 62, 6.9), and 2.2% had another drug use disorder (95% CI: 2.0, 2.4). More males than females had substance use disorders: 9.5% of males (95% CI: 8.5, 10.5) and 3.6% of females (95% CI: 3.2, 4.0) met criteria for an alcohol use disorder, and 3.2% of males (95% CI: 2.8, 3.6) and 1.3% of females (95% CI: 0.9, 1.7) met criteria for another drug use disorder within the past 12 months. The prevalence of substance use disorders decreased with increasing age: 10.5% of respondents aged 18-34 years met criteria for an alcohol use disorder and 4.8% met criteria for a drug use disorder. The rates of these disorders among those aged 55 years or older were 1.8% and 0.1%, respectively. Substance use disorders were more prevalent among the unemployed, those who had never married and those who were Australian-born. Conclusions. The prevalence of substance use disorders in the Australian population is comparable to that in other English-speaking countries.