A prospective cohort study found no significant difference in the incidence of tardive dyskinesia (TD) between patients treated with conventional and atypical antipsychotics; the incidence and prevalence were similar to previous findings at the same site two decades ago.

The authors comment that most previous studies comparing conventional with atypical antipsychotics have not focussed on TD. They therefore carried out a prospective cohort study similar in design to one carried out at the some site in the 1980’s to examine current incidence and prevalence, and relationship to antipsychotic drug therapy. Participants were patients at a community mental health centre who were free from TD at baseline (between November 2000 to May 2003). They were examined every six months for up to four years for signs of TD using standard criteria.

There were 352 patients in the study, most of whom were receiving antipsychotic drugs at baseline - most (64%) were receiving atypical antipsychotics only; 23% were receiving conventional antipsychotics only; and 14% were receiving both. Only 26 had never received conventional antipsychotics. Patients who had only received atypical antipsychotics did not have a significantly different risk of being diagnosed with TD than those who had received only conventional drugs, with an adjusted rate ratio of 0.68 (95% CI, 0.29 to 1.64). Compared with the previous study at the same site in the 1980’s, the incidence and prevalence of TD was similar.

The authors conclude that according to their results, the incidence of TD with recent exposure to atypical antipsychotics was closer to that with conventional drugs than found in previous studies. Despite the high proportion of patients taking atypical drugs, the incidence and prevalence of TD was relatively unchanged since the 1980’s. They therefore recommend that clinicians should continue to monitor for TD in patients being treated with any antipsychotic drug.

[Editor’s note: taken from the abstract as full text not available.]