Risk factors for tardive dyskinesia.

Three hundred and fifty three patients who had been on antipsychotics for three months or more were assessed using Simpson Tardive Dyskinesia Rating Scale. 40.2% of these patients, who merited a diagnosis of probable Tardive Dyskinesia (TD) by the Schooler and Kane criteria, were reassessed three months later and 25.5% of the total sample were found to have persistent TD. Age, total antipsychotic dosage and duration of antipsychotic exposure were found to be positively correlated with persistent TD.