Effects of Antipsychotic Treatment on Tardive Dyskinesia: A 6-Month Evaluation of Patients From the European Schizophrenia Outpatient Health Outcomes (SOHO) Study

Objective: To compare the incidence and persistence of tardive dyskinesia between patients diagnosed with schizophrenia (ICD-10 and/or DSM-IV) who were treated with second-generation antipsychotics and first-generation antipsychotics in routine clinical practice.

Method: The European Schizophrenia Outpatient Health Outcomes (SOHO) study is a 3-year, prospective, observational study. Each country had a start date for patient enrollment before October 2000. All enrollment was completed by June 30, 2001. A simple, global measure of tardive dyskinesia was rated by participating clinicians. For the current analysis, data at baseline, 3 months, and 6 months were analyzed using a generalized estimating equation model.

Results: Second-generation antipsychotics conferred a lower risk for tardive dyskinesia at 6 months than first-generation antipsychotics (0.9% vs. 3.8%, odds ratio [OR] = 0.29, 95% confidence interval [CI] = 0.18 to 0.46). In addition, patients with tardive dyskinesia at baseline who were receiving second-generation antipsychotics were less likely than patients receiving first-generation antipsychotics to have tardive dyskinesia symptoms at 6 months (43.6% vs. 60.8%, OR = 0.50, 95% CI = 0.30 to 0.85). A sensitivity analysis suggested no bias related to pharmaceutical industry financial support.

Conclusion: The results suggest that the relative advantage of second-generation antipsychotics in terms of lower rates of incidence and persistence of tardive dyskinesia, observed in technical randomized controlled trials, generalizes to routine clinical care.