Inter-rater reliability of twelve diagnostic systems of schizophrenia.

The present and past symptomatology of 31 chronic schizophrenics was rated by four independent judges, two experienced clinical psychiatrists and two psychiatric residents, in a context more representative of actual clinical practice than most research studies. Ratings were made on 64 symptoms derived from 12 diagnostic systems, based on either live or videotaped interviews for present symptomatology and case records for past symptomatology. Inter-rater reliabilities were higher for present than for past symptoms, and in general did not approach those reported for highly trained raters. There were no differences between live and videotaped interviews. Diagnostic systems differed widely in rater agreement. The most consistent across both past and present symptomatology were the systems of Langfeldt, Schneider, and DSM-III, for which the level of reliability was consistent with other studies.