Clinical trials suggest that patients receiving atypical antipsychotics are less likely to develop movement disorders than those receiving conventional antipsychotics. We determined incidence of treatment-emergent TD during long-term treatment of schizophrenia or schizoaffective disorder with aripiprazole or haloperidol.

In a post hoc analysis of pooled data collected from two 52-week double-blind trials involving 1,294 patients treated either with aripiprazole 20-30mg/d (n=861) or haloperidol 5-10mg/d (n=433), treatment-emergent TD was identified based on Research Diagnostic Criteria (RDC) extracted from the Abnormal Involuntary Movement Scale (AIMS) (Schooler-Kane criteria).

In patients without baseline TD (n=1,177), the rate of new-onset TD at any time point following randomization was 5.09% for aripiprazole-treated patients and 11.76% for haloperidol-treated patients (p<0.0001). Using a stricter definition of RDC-defined TD on the last two study visits, new-onset TD was seen in 0.25% of aripiprazole-treated patients versus 4.09% of haloperidol-treated patients (p<0.0001), and was mild in 100% of aripiprazole-treated patients, and mild in 68.75% and moderate or severe in 31.25% of haloperidol-treated patients. Mean baseline to endpoint increase in AIMS score was significantly greater in haloperidol- versus aripiprazole-treated patients in both LOCF (n=1177, p=0.0001) and OC (n=427, p<0.0001) analyses.

Aripiprazole is associated with a significantly reduced risk of new-onset tardive dyskinesia compared with haloperidol in patients with schizophrenia or schizoaffective disorder treated for up to 52 weeks. Aripiprazole's dopamine D2 partial agonist and/or serotonin 5HT2A antagonist receptor binding profile may contribute to this.