BACKGROUND: A number of western studies have suggested that the 6-month duration requirement of generalized anxiety disorder (GAD) does not represent a critical threshold in terms of onset, course, or risk factors of the disorder. No study has examined the consequences of modifying the duration requirement across a wide range of correlates in both developed and developing countries. METHOD: Population surveys were carried out in seven developing and 10 developed countries using the WHO Composite International Diagnostic Interview (total sample=85,052). Prevalence and correlates of GAD were compared across mutually exclusive GAD subgroups defined by different minimum duration criteria. RESULTS: Lifetime prevalence estimates for GAD lasting 1 month, 3 months, 6 months and 12 months were 7.5%, 5.2%, 4.1% and 3.0% for developed countries and 2.7%, 1.8%, 1.5% and 1.2% for developing countries, respectively. There was little difference between GAD of 6 months' duration and GAD of shorter durations (1-2 months, 3-5 months) in age of onset, symptom severity or persistence, co-morbidity or impairment. GAD lasting >or=12 months was the most severe, persistently symptomatic and impaired subgroup. CONCLUSIONS: In both developed and developing countries, the clinical profile of GAD is similar regardless of duration. The DSM-IV 6-month duration criterion excludes a large number of individuals who present with shorter generalized anxiety episodes which may be recurrent, impairing and contributory to treatment-seeking. Future iterations of the DSM and ICD should consider modifying the 6-month duration criterion so as to better capture the diversity of clinically salient anxiety presentations.

These activities were supported by the United States National Institute of Mental Health (R01MH070884), the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, the US Public Health Service (R13-MH066849, R01-MH069864, and R01 DA016558), the Fogarty International Center (FIRCA R03-TW006481). The ESEMeD project is funded by the European Commission (Contracts QLG5-1999-01042; SANCO 2004123), the Piedmont Region (Italy), Fondo de Investigación Sanitaria, Instituto de Salud Carlos III, Spain (FIS 00/0028), Ministerio de Ciencia y Tecnología, Spain (SAF 2000-158-CE), Departament de Salut, Generalitat de Catalunya, Spain, Instituto de Salud Carlos III (CIBER CB06/02/0046, RETICS RD06/0011 REM-TAP). The World Mental Health Japan (WMHJ) Survey is supported by the Grant for Research on Psychiatric and Neurological Diseases and Mental Health (H13-SHOGAI-023, H14-TOKUBETSU-026, H16-KOKORO-013) from the Japan Ministry of Health, Labour and Welfare. The Mexican National Comorbidity Survey (MNCS) is supported by The National Institute of Psychiatry Ramon de la Fuente (INPRFMDIES 4280) and by the National Council on Science and Technology (CONACyT-G30544- H). The South Africa Stress and Health Study (SASH) is supported by the US National Institute of Mental Health (R01-MH059575). The Ukraine Comorbid Mental Disorders during Periods of Social Disruption (CMDPSD) study is funded by the US National Institute of Mental Health (RO1-MH61905). The US National Comorbidity Survey Replication (NCS-R) is supported by the National Institute of Mental Health (NIMH; U01-MH60220) with supplemental support from the Robert Wood Johnson Foundation (RWJF; Grant 044708).