Prevalence and structure of anxiety-depression in an Australian community sample

Aim of the study To describe the prevalence and factor structure of anxiety-depression in a community sample and to derive indicators for treatment planning. Subject or material and methods A sample of 398 members of the Electoral Roll for the New England region of Australia were recruited at random and completed the Zung Self-rating Anxiety Scale and the Zung Self-rating Depression Scale. Results The prevalence of anxiety-depression was 28.1%, over twice that for either anxiety or depression alone. The anxiety-depression construct was comprised of four underlying factors: Cognitive Agitation & Depressed Mood, Pessimism, Cardiovascular Reactivity, and Pain & Sleep Disturbance. There were different patterns of these four factors across Anxiety-only, Depression-only and combined anxiety-depression, with evidence for a unique symptomatological profile for participants with clinically significant levels of anxiety-depression. Discussion Anxiety-depression comorbidity was relatively common in this community sample of Australians, with over a quarter of participants meeting the cutoff for clinically significant scores on the combined SAS-SDS construct. These results also highlight the need to consider the presence of clinically significant anxiety-depression as representing a larger proportion of this sample than either anxiety or depression alone. Conclusions Treatment decisions for anxiety and depression need to go beyond consideration of the two disorders separately to include the underlying factor severity of the combined construct of anxiety-depression.