Randomised double-blind comparison of the incidence of tardive dyskinesia in patients with schizophrenia during long-term treatment with olanzapine or haloperidol.

ABSTRACT

BACKGROUND: Tardive dyskinesia is important in the side-effect profile of antipsychotic medication. AIMS: The development of tardive dyskinesia was evaluated in patients treated with double-blind, randomly assigned olanzapine or haloperidol for up to 2.6 years. METHODS: Tardive dyskinesia was assessed by the Abnormal Involuntary Movement Scale (AIMS) and Research Diagnostic Criteria for Tardive Dyskinesia (RD-TD), it was defined as meeting RD-TD criteria at two consecutive assessments. The risk of tardive dyskinesia, the relative risk, incidence rate, and incidence rate ratio were estimated. RESULTS: The relative risk of tardive dyskinesia for the overall follow up period for haloperidol (n = 522) v. olanzapine (n = 1192) was 2.66 (95% CI = 1.50-4.70). Based on data following the initial six weeks of observation (during which patients underwent medication change and AIMS assessments as frequently as every three days), the one-year risk was 0.52% with olanzapine (n = 513) and 7.45% with haloperidol (n = 114). The relative risk throughout this follow-up period was 11.37 (95% CI = 2.21-58.60). CONCLUSION: Our results indicated a significantly lower risk of tardive dyskinesia with olanzapine than with haloperidol.