title: Understanding cross-national differences in depression prevalence.
abstract: BACKGROUND. Previous epidemiological studies indicate large cross-national differences in prevalence of depression.
  
  
  METHODS
  At 15 centres in 14 countries. 25,916 primary care patients were screened for common mental disorders. A stratified random sample of 5,447 primary care patients completed a baseline diagnostic assessment and 3,197 completed a 12-month follow-up assessment. Psychiatric symptoms and diagnoses were assessed using the Composite International Diagnostic Interview (CIDI). Interviewer-rated disability was assessed using the Social Disability Schedule (SDS).
  
  
  RESULTS
  Prevalence of current major depression varied 15-fold across centres. When centres were divided into three groups according to prevalence rates, the symptom pattern or latent structure of depressive illness was generally similar at low-, medium-, and high-prevalence centres. Depression was universally associated with disability, but this association varied significantly (t = 3.51, P = 0.0005) across centres. At higher-prevalence centres, depression was associated with lower levels of impairment. At 1 year follow-up, higher prevalence centres had both significantly higher rates of depression onset (t = 3.11, P = 0.002) and higher rates of persistence among those depressed at baseline (t = 2 49, P = 0.013).
  
  
  CONCLUSIONS
  Large cross-national variations in depression prevalence cannot be attributed to 'category fallacy' (cross-national differences in the nature or validity of depressive disorder). Use of identical measures and diagnostic criteria may actually identify different levels of depression severity in different countries or cultures. Cross-national differences in the onset and outcome of depression may reflect either true prevalence differences or differences in diagnostic threshold.
authors.affiliation: Center for Health Studies, Group Health Cooperative, Seattle, WA 98101-1448, USA.
authors.forename: G E
authors.initials: GE
authors.lastname: Simon
authors.forename: D P
authors.initials: DP
authors.lastname: Goldberg
authors.forename: M
authors.initials: M
authors.lastname: Von Korff
authors.forename: T B
authors.initials: TB
authors.lastname: Ustün
mesh_terms: D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D005500:Follow-Up Studies; D006801:Humans; D008403:Mass Screening / Q000706:statistics & numerical data; D011320:Primary Health Care / Q000706:statistics & numerical data; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D011594:Psychometrics; D015203:Reproducibility of Results; D012917:Social Adjustment; D014944:World Health Organization