Olanzapine for patients with treatment-resistant schizophrenia: a naturalistic case-series outcome study

Abstract

Objective: This prospective, consecutive case-series outcome investigation evaluates the effectiveness of olanzapine in 16 patients with treatment-resistant schizophrenia.

Method: Treatment resistance was defined as nonresponsiveness to at least 3 antipsychotic drugs from at least 2 different chemical classes. A minimum baseline score on the Brief Psychiatric Rating Scale (BPRS) of 45 was required for enrolment. Outcome evaluation measures included the BPRS, Global Assessment Scale (GAS), and Abnormal Involuntary Movement Scale (AIMS).

Results: Subjects (n = 16) has a mean age of 40 years and mean duration of illness of 16 years. Olanzapine treatment was initiated at 5 mg daily and was increased based on clinical judgement up to a maximum of 40 mg daily. Significant decreases in mean BPRS (P < 0.001) and GAS (P < 0.01) scores were observed at weeks 4, 8, 12, and 16, compared with baseline. Eight of 16 patients responded to olanzapine, as defined by a 20% decrease in BPRS score by week 16. Dyskinetic movements significantly increased at week 4 (P < 0.01) but did not differ from baseline at weeks 8 and 16.

Conclusion: These results suggest that olanzapine at moderate to high doses may offer an effective treatment for a significant proportion of patients with schizophrenia nonresponsive to multiple trials of conventional antipsychotics. A randomized controlled trial is encouraged to validate these findings, and comparative trials are required to determine when clinicians should consider this approach.