Objective: To compare the 9-month cumulative incidence of tardive dyskinesia (TD) with risperidone to that with haloperidol in older patients.
Design: A prospective longitudinal study.
Setting: An outpatient psychiatric clinic.
Participants: Subjects were middle-aged and older (mean age 66 years) patients with schizophrenia, dementia, mood disorders, or other conditions with psychotic symptoms or severe behavioral disturbances. Sixty-one patients on risperidone were matched with 61 patients from a larger sample of haloperidol-treated patients in regard to age, diagnosis, and length of pre-enrollment neuroleptic intake to create clinically comparable groups. The median daily dose of each medication was 1.0 mg.
Measurements: Abnormal Involuntary Movement Scale, modified Simpson-Angus' scale for extrapyramidal symptoms, Brief Psychiatric Rating Scale, and Mini-Mental State Examination were administered at baseline, 1 month, and 3, 6, and 9 months. The diagnosis of TD was based on specific research criteria. The raters were blind to the patient's medication status.
Results: Life table analysis revealed that patients treated with haloperidol were significantly more likely to develop TD than patients treated with risperidone (P < .05, Peto-Prentice).
Conclusions: The atypical antipsychotic risperidone is significantly less likely to result in TD than the conventional neuroleptic haloperidol in a high-risk group of older patients, at least over a 9-month period.