Clozapine Treatment and Predictors of Response in Patients with Schizophrenia

To search for the predictive clinical variables in schizophrenic patients responding to clozapine, the authors retrospectively examined the clinical variables of the schizophrenics who were treated with clozapine for at least 6 months at Inha University Hospital either on an outpatient basis or by hospitalization. The subjects were schizophrenic patients who satisfied the DSM-IV diagnostic criteria and were treated with clozapine for at least 6 months in the outpatient and inpatient departments. Among the 41 schizophrenic patients who were treated with clozapine, 28 patients were included in the final analysis, with 13 patients being excluded due to the insufficient duration of their clozapine treat-ment. Subjects were classified into 2 groups consisting of responders and non-responders, depending to their CGI scores. Using the SAS package program, all data were analyzed by Fisher’s exact test, Mantel-Haenszel chi test and multiple regression test. Among the total of 28 schizophrenic patients (male 18, female 10) included in the final analysis, 15 schizophrenics responded to clozapine treatment. The age of onset, number of negative symptoms and clinical subtypes were significantly different between the two groups. Gender, mode of onset, number of hospitalizations, duration of hospitalization, family history of psychosis, maximal dose of clozapine and duration of clozapine treatment did not differ significantly between the two groups. This study suggests that some schizophrenic patients respond well to clozapine treatment. In this study, those patients responding well to clozapine treatment were more likely to have a higher age of onset, to experience fewer negative symptoms and to belong to the paranoid subtype.