Flexible system for the diagnosis of schizophrenia: report from the WHO International Pilot Study of Schizophrenia.

Behavioral data on a large patient group were collected by investigators from nine countries in the International Pilot Study of Schizophrenia, sponsored by the World Health Organization. The data on half the group were analyzed to derive a system of 12 signs and symptoms for the identification of schizophrenia, as this disorder is diagnosed in many centers throughout the world. The findings were replicated with the other half of the patient group. The criteria constitute an operational method for identifying patients who would be commonly considered schizophrenic in many centers.