Lifetime prevalence, demographic risk factors, and diagnostic validity of nonaffective psychosis as assessed in a US community sample. The National Comorbidity Survey.

BACKGROUND

We seek to estimate lifetime prevalence and demographic correlates of nonaffective psychosis in the US population assessed by a computer-analyzed structured interview and a senior clinician.

METHODS

In the National Comorbidity Survey, a probability subsample of 5877 respondents were administered a screen for psychotic symptoms. Based on the response to this screening, detailed follow-up interviews were conducted by mental health professionals (n = 454). The initial screen and clinical reinterview were reviewed by a senior clinician. Results are presented for narrowly (schizophrenia or schizophreniform disorder) and broadly (all nonaffective psychoses) defined psychotic illness.

RESULTS

One or more psychosis screening questions were endorsed by 28.4% of individuals. By computer algorithm, lifetime prevalences of narrowly and broadly defined psychotic illness were 1.3% and 2.2%, respectively. Of those assigned a narrow diagnosis by the computer, the senior clinician assigned narrow and broad diagnoses to 10% and 37%, respectively. By clinician diagnosis, lifetime prevalence rates of narrowly and broadly defined psychosis were 0.2% and 0.7%, respectively. A clinician diagnosis of nonaffective psychosis was significantly associated with low income; unemployment a marital status of single, divorced, or separated; and urban residence Clinician confirmation of a computer diagnosis was predicted by hospitalization, neuroleptic treatment, duration of illness, enduring impairment, and thought disorder.

CONCLUSIONS

Lifetime prevalence estimates of psychosis in community samples are strongly influenced by methods of assessment and diagnosis. Although results using computer algorithms were similar in the National Comorbidity Survey and Epidemiologic Catchment Area studies, diagnoses so obtained agreed poorly with clinical diagnoses. Accurate assessment of psychotic illness in epidemiologic samples may require collection of extensive contextual information for clinician review.