Incidence and persistence of tardive dyskinesia and extrapyramidal symptoms in schizophrenia

Although it has been suggested that second-generation antipsychotics (SGA) may reduce the rate of prevalent tardive dyskinesia (TD), little is known about the incidence and outcome of TD in those exposed exclusively to SGA. The incidence and subsequent persistence of TD and extrapyramidal symptoms (EPS) was calculated in a cohort of patients with schizophrenia treated predominantly with SGA. This cohort of more than 10,000 patients with schizophrenia was seen six times over a period of two years. Dichotomous measures of EPS and TD were used to calculate the yearly incidence rates of TD and EPS as well as their subsequent cumulative persistence rate in a subset of 9104 and 6285 patients at risk for TD and EPS, respectively. Of 9104 individuals who did not present with TD at baseline, 138 developed TD, yielding a TD incidence rate of 0.74% (95% CI: 0.62, 0.87) and a subsequent cumulative persistence rate of 80%. Of 6285 individuals without EPS at baseline, 464 developed EPS yielding an incidence rate of 3.7% (95% CI: 3.4, 4.0) and a subsequent cumulative persistence rate of 82%. Incidence rates of TD and EPS may be low in the SGA era. However, once emerged, these disorders prove persistent, suggesting strong moderators effects of underlying predisposing factors.