Background: The proposed revisions of the ICD and DSM diagnostic systems have led to increased interest in evaluation of diagnostic criteria. This report focuses on the DSM-IV requirement that episodes of generalized anxiety disorder (GAD) must persist for at least 6 months. Community epidemiological data are used to study the implications of changing this requirement in the range 1-12 months for estimates of prevalence, onset, course, impairment, co-morbidity, associations with parental GAD, and sociodemographic correlates.
Method: Data come from the US National Comorbidity Survey Replication (NCS-R), a US household survey carried out during 2001-2003. Version 3.0 of the WHO Composite International Diagnostic Interview (WMH-CIDI) was used to assess DSM-IV anxiety disorders, mood disorders, substance disorders, and impulse-control disorders.
Results: Lifetime, 12-month, and 30-day prevalence estimates of DSM-IV GAD changed from 6.1%, 2.9%, and 1.8% to 4.2-12.7%, 2.2-5.5%, and 1.6-2.6% when the duration requirement was changed from 6 months to 1-12 months. Cases with episodes of 1-5 months did not differ greatly from those with episodes of > or = 6 months in onset, persistence, impairment, co-morbidity, parental GAD, or sociodemographic correlates.
Conclusions: A large number of people suffer from a GAD-like syndrome with episodes of < 6 months duration. Little basis for excluding these people from a diagnosis is found in the associations examined here.