Background: Past episodes of depressive or anxiety disorders and subthreshold symptoms have both been reported to predict the occurrence of depressive or anxiety disorders. It is unclear to what extent the two factors interact or predict these disorders independently.
Aims: To examine the extent to which history, subthreshold symptoms and their combination predict the occurrence of depressive (major depressive disorder, dysthymia) or anxiety disorders (social phobia, panic disorder, agoraphobia, generalised anxiety disorder) over a 2-year period.
Method: This was a prospective cohort study with 1167 participants: the Netherlands Study of Depression and Anxiety. Anxiety and depressive disorders were determined with the Composite International Diagnostic Interview, subthreshold symptoms were determined with the Inventory of Depressive Symptomatology-Self Report and the Beck Anxiety Inventory.
Results: Occurrence of depressive disorder was best predicted by a combination of a history of depression and subthreshold symptoms, followed by either one alone. Occurrence of anxiety disorder was best predicted by both a combination of a history of anxiety disorder and subthreshold symptoms and a combination of a history of depression and subthreshold symptoms, followed by any subthreshold symptoms or a history of any disorder alone.
Conclusions: A history and subthreshold symptoms independently predicted the subsequent occurrence of depressive or anxiety disorder. Together these two characteristics provide reasonable discriminative value. Whereas anxiety predicted the occurrence of an anxiety disorder only, depression predicted the occurrence of both depressive and anxiety disorders.