Prevalence and correlates of the proposed DSM-5 diagnosis of Chronic Depressive Disorder

Context: The draft proposal to add Chronic Depressive Disorder to DSM-5 will combine DSM-IV Dysthymic Disorder and Major Depressive Disorder, with chronic specifier, into a single diagnosis.

Objective: The objective of this study is to estimate the prevalence and correlates of the proposed DSM-5 diagnosis of Chronic Depressive Disorder using unit record data from the 2007 Australian National Survey of Mental Health and Wellbeing.

Design: Secondary analysis of a nationally representative household survey.

Setting: Urban and rural census tracts.

Participants: One individual between the ages of 16 and 85 years from 8841 households was interviewed for the survey.

Main outcome measure: Lifetime prevalence estimates for chronic and non-chronic depression were determined using data from the World Health Organization's Composite International Diagnostic Interview, version 3.0 (WMH-CIDI 3.0).

Results: Chronic depression of at least two years' duration had a lifetime prevalence of 4.6% (95% CI: 3.9-5.3%) and was found in 29.4% (95% CI: 25.6-33.3%) of individuals with a lifetime depressive disorder. Higher rates of psychiatric co-morbidity (OR=1.42; 95% CI=1.26-1.61), older age (OR=1.04; 95% CI=1.02-1.05), a younger age of onset (OR=0.97; 95% CI=0.95-0.98) and more frequent episodes of depression (OR=1.75; 95% CI=1.07-2.86) were found to be significant correlates of chronic depression. The first episode of depression for individuals with chronic depression often developed after the death of someone close (OR=2.38; 95% CI 1.16-5.79).

Conclusions: Chronic depression is highly prevalent among community-residing persons and has a set of correlates that discriminate it from non-chronic depression. The distinction between chronic and non-chronic depression proposed for DSM-5, in the form of Chronic Depressive Disorder, seems to be warranted.