Rethinking the duration requirement for generalized anxiety disorder: evidence from the National Comorbidity Survey Replication.

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.