Background. This paper reports population data on DSM-IV generalized anxiety disorder from the Australian National Survey of Mental Health and Well-Being.

Methods. The data were obtained from a nationwide household survey of adults using a stratified multi-stage sampling process. A response rate of 78·1% resulted in 10641 persons being interviewed. Diagnoses were made using the Composite International Diagnostic Interview. The interview was computerized and conducted by trained lay interviewers.

Results. Prevalence in the total sample was 2·8% for 1-month GAD and 3·6% for 12-month GAD. Persons over 55 years of age were less likely to have GAD than those in the younger age groups. Logistic regression analysis also showed that a diagnosis of GAD was significantly associated with being of younger to middle age, being separated divorced or widowed, not having tertiary qualifications or being unemployed. Co-morbidity with another affective, anxiety, substance use or personality disorders was common, affecting 68% of the sample with 1-month DSM-IV GAD. GAD was associated with significant disablement, and 57% of the sample with DSM-IV GAD had consulted a health professional for a mental health problem in the prior 12 months.

Conclusions. The survey provides population data on DSM-IV GAD and its correlates. GAD is a common disorder that is accompanied by significant morbidity and high rates of co-morbidity with affective and anxiety disorders, and is associated with marital status, education, employment status, but not sex. Changes to DSM-IV diagnostic criteria did not appear to affect the prevalence rate compared to previous population surveys.