Comorbidity in Australia: findings of the 2007 National Survey of Mental Health and Wellbeing

Objective: The aim of the present study was to report the prevalence and patterns of 12 month comorbidity in the 2007 National Survey of Mental Health and Wellbeing (2007 NSMHWB). In this paper the comorbidity between common mental disorders (affective, substance use and anxiety) and between physical and mental disorders is examined. Method: The 2007 NSMHWB was a nationally representative household survey of 8841 Australian adults (16-85 years) that assessed participants for symptoms of the most prevalent ICD-10 mental disorders. Results: The common mental disorder classes (affective, anxiety and substance use disorders) often occur together and 25.4% of persons with an anxiety, affective or substance use disorder had at least one other class of mental disorder. A small proportion (3.5%, 95% confidence interval (CI) = 2.3-4.7%) had all three classes of disorder. Mental disorder and physical disorder comorbidity was also common, with 28% (95%CI = 25.1-30.9%) of those with a chronic physical disorder also having a mental disorder. Comorbidity was associated with greater severity and greater health service use. Conclusions: Comorbidity is widespread and remains a significant challenge for the delivery of effective health-care services and treatment.