Abstract

Context:Recent general population surveys of psychotic disorders have found low lifetime prevalences.However, this may be owing to methodological problems.Few studies have reported the prevalences of all specific psychotic disorders.Objective: To provide reliable estimates of the lifetime prevalences of specific psychotic disorders.Design: General population survey.Setting and Participants: A nationally representative sample of 8028 persons 30 years or older was screened for psychotic and bipolar I disorders using the Composite International Diagnostic Interview, self-reported diagnoses, medical examination, and national registers.Those selected by the screens were then reinterviewed with the Structured Clinical Interview for DSM-IV.Bestestimate DSM-IV diagnoses were formed by combining the interview and case note data.Register diagnoses were used to estimate the effect of the nonresponders.Main Outcome Measures: Diagnosis of any psy-chotic or bipolar I disorder according to the DSM-IV criteria. Results:The lifetime prevalence of all psychotic disorders was 3.06% and rose to 3.48% when register diagnoses of the nonresponder group were included.Lifetime prevalences were as follows: 0.87% for schizophrenia, 0.32% for schizoaffective disorder, 0.07% for schizophreniform disorder, 0.18% for delusional disorder, 0.24% for bipolar I disorder, 0.35% for major depressive disorder with psychotic features, 0.42% for substance-induced psychotic disorders, and 0.21% for psychotic disorders due to a general medical condition.The National Hospital Discharge Register was the most reliable of the screens (=0.80).Case notes supplementing the interviews were essential for specific diagnoses of psychotic disorders.Conclusions: Multiple sources of information are essential for accurate estimation of lifetime prevalences of psychotic disorders.The use of comprehensive methods reveals that their lifetime prevalence exceeds 3%.