Prevalence of tardive dyskinesia in a clinic population.

The reported prevalence of tardive dyskinesia (TD) widely ranges from 0.5% to 70%. This variability is probably due to many factors, including different patient characteristics, drug treatment exposures, and investigator biases. The aim of this study was to evaluate the prevalence, severity, and symptom type of TD in all 646 patients residing in a psychiatric hospital. Each patient was assessed by a psychiatrist and a neurologist with a special rating scale after drug dose had been stabilized for a minimum of 1 week. The overall prevalence was 32%, with a slightly higher rate and more severe symptoms in women. Age positively correlated with increasing prevalence and severity of TD. Psychiatric diagnosis and duration of neuroleptic therapy were not significantly correlated with TD prevalence. The results are generally consistent with the majority of findings in other studies of the epidemiology of TD.