Frequency of extrapyramidal adverse reactions in schizophrenic outpatients treated with risperidone, olanzapine, quetiapine or haloperidol -: Results of the EIRE study

Objectives: The EIRE (Estudio de Investigacion de Resultados en Esquizofrenia - Outcomes Research Study in Schizophrenia) study was initiated in order to assess the frequency of adverse reactions [extrapyramidal symptoms (EPS), hyperprolactinaemia, sexual dysfunction and weight gain] caused by atypical antipsychotics and haloperidol in patients with schizophrenia during routine treatment in clinical practice. This paper presents the results of the assessment of extrapyramidal adverse reactions. Patients and study design: Outpatients diagnosed with schizophrenia according to the Diagnostic and Statistical Manual of mental disorders, 4th edition (DSM-IV), criteria and receiving a single antipsychotic (risperidone, olanzapine, quetiapine or haloperidol) for at least 4 weeks were consecutively recruited. In this cross-sectional and non-interventional study data were collected in a single visit; this included demographic and clinical characteristics, current antipsychotic and concomitant treatment, and data on several adverse effects listed in a modified version of the UKU (Udvalg for Kliniske Undersogelser - Committee on Clinical Investigations) scale. For paired comparisons of the frequency of adverse reactions between treatments the Chi-squared (chi(2)) test was used. For estimation of the risk of a given adverse reaction with a given treatment a logistic regression method was used. Results: 636 evaluable patients (of 669 recruited) were assessed. The frequency of EPS with haloperidol (78.3% of the cases) was higher than with risperidone (55.1%), quetiapine (39.5%) and olanzapine (35.8%) [chi(2): p < 0.05], and the difference between risperidone and olanzapine was also statistically significant (chi(2): p < 0.05). Very similar results were obtained in the individualised analysis of the items as regards the occurrence of akathisia, which was also more frequent in the haloperidol (36.8%) and risperidone (19.7%) groups than in the olanzapine (11.4%) and quetiapine (2.6%) groups (chi(2): p < 0.05). Olanzapine, quetiapine and risperidone also showed a lower risk of EPS than haloperidol when adjusting by dose. Conclusion: Our results suggest that the atypical antipsychotics studied are less likely to induce extrapyramidal adverse reactions compared with haloperidol in stabilised patients, although these reactions are still common.