Clozapine for Treatment-refractory Schizophrenia, Schizoaffective Disorder, and Psychotic Bipolar Disorder: a 24-month Naturalistic Study

Background: The aim of this study was to evaluate the 24-month response to clozapine in patients with schizophrenia, schizoaffective disorder, or psychotic bipolar disorder.

Method: Ninety-one psychotic patients with a principal DSM-III-R diagnosis of schizophrenia (N = 31), schizoaffective disorder (N = 26), or bipolar disorder with psychotic features (N = 34) were treated naturalistically with clozapine at flexible dosages over a 24-month period. Improvement was assessed by the 18-item Brief Psychiatric Rating Scale and the Clinical Global Impressions-Severity of Illness scale.

Results: All patients showed significant improvement 24 months from intake (p < .001). Such an improvement was significantly greater among patients with schizoaffective disorder or bipolar disorder than in patients with schizophrenia (p < .05). The presence of suicidal ideation at intake predicted greater improvement at endpoint.

Conclusion: Clozapine appears to be effective and relatively well tolerated in acute and long-term treatment of patients with psychotic bipolar disorder or schizoaffective disorder who have not responded to conventional pharmacotherapies.