Diagnostic significance of Schneider's first-rank symptoms in schizophrenia. Comparative study between schizophrenic and non-schizophrenic psychotic disorders.

BACKGROUND

Despite the lack of consistent empirical support, modern diagnostic criteria of schizophrenia give particular emphasis to Schneider's first-rank symptoms (FRSs).

AIMS

To examine the diagnostic significance of FRSs for schizophrenia by trying to overcome the limitations of previous studies.

METHODS

This study examined the diagnostic accuracy of FRSs for schizophrenia in 660 in-patients with the full spectrum of functional psychotic disorders. Schizophrenia was diagnosed according to three criteria: DSM-III-R broad, DSM-III-R narrow and Feighner, the latter being considered as the gold standard because it does not give particular emphasis of FRSs.

RESULTS

FRSs were highly prevalent in both schizophrenia and non-schizophrenic psychoses. The likelihood ratios (and 95% CI) of one or more FRSs for Feighner, DSM-III-R narrow and DSM-III-R broad schizophrenia were 1.06 (0.94-1.20), 1.23 (1.09-1.39) and 1.73 (1.44-2.08), respectively. These data indicate that FRSs do not significantly increase the likelihood of having schizophrenia.

CONCLUSIONS

FRSs are not useful in differentiating schizophrenia from other psychotic disorders. Diagnostic systems for schizophrenia that are heavily based on these symptoms may arise from a tautological definition of the disorder.