Severity of depressive episodes during the course of depressive disorder

It is not clear whether the severity of depressive episodes changes during the course of depressive disorder.

To investigate whether the severity of depressive episodes increases during the course of illness.

Using a Danish nationwide case register, all psychiatric in-patients and out-patients with a main ICD-10 diagnosis of a single mild, moderate or severe depressive episode at the end of first contact were identified. Patients included in the study were from the period 1994-2003.

A total of 19 392 patients received a diagnosis of a single depressive episode at first contact. The prevalence of severe depressive episodes increased from 25.5% at the first episode to 50.0% at the 15th episode and the prevalence of psychotic episodes increased from 8.7% at the first episode to 25.0% at the 15th episode. The same pattern was found regardless of gender, age at first contact and calendar year.

The increasing severity of depressive episodes emphasises the importance of early and sustained prophylactic treatment.