Background. Lifetime and 12-month prevalence estimates of mental disorders consistently reported in large-scale community surveys have met with deserved scepticism. A crucial variable is the extent to which people who are considered cases are also disabled by their symptoms. In a national population survey, we hypothesized that an administratively significant proportion of persons with anxiety or depressive disorders according to ICD-10 and DSM-IV would report no disability.

Methods. Interviews were sought on a nationally representative sample of people aged 18 and over across Australia. The Composite International Diagnostic Interview on laptop (CIDI-A) was used by professional survey interviewers to identify persons meeting ICD-10 or DSM-IV criteria for anxiety or depressive disorders in the previous 4 weeks, together with self-reported data on associated disability and medical consultations for the same period.

Results. In an achieved sample of 10641 persons (response rate = 78%), no disability in daily life was reported by 28% of persons with an anxiety disorder and 15% with a depressive disorder by ICD-10 criteria; and by 20·4% and 13·9% respectively by DSM-IV. Non-disabled respondents had lower scores on two measures of psychological distress and markedly lower rates for having consulted a doctor for their symptoms.

Conclusion. The ICD-10 and DSM-IV criteria for anxiety and depressive disorders, when applied to the information on symptoms elicited by the CIDI-A, inadequately discriminate between people who are and are not disabled by their symptoms. There may be a group of highly symptomatic people in the general population who tolerate their symptoms and are not disabled by them.