Objective: To study adjunctive medications used with antipsychotic agents in schizophrenia via comparisons of antidepressant, anxiolytic and antiparkinsonian co-prescribing.
Method: In the context of a national naturalistic prospective observational study, a database containing all the prescriptions from 100 French psychiatrists during the year 2002 was analysed. The inclusion criteria were a diagnosis of schizophrenia or schizoaffective disorder and age over 18. A log-linear model and generalised linear mixed models were used.
Results: In all 5,257 prescriptions for 922 patients were analysed. The proportion of patients who were prescribed an antiparkinsonian drug was 32.9%. Amisulpride, haloperidol, phenothiazines with a sedative action and depot typical antipsychotics proved more likely to be prescribed with antiparkinsonians. The frequency of antidepressant and anxiolytic prescriptions was 51.2% and 52.3%, respectively. Associations between atypical antipsychotics (except clozapine) and antidepressants were positive while associations between typical antipsychotics and antidepressants were not. There were no differences among antipsychotics for the prescription of anxiolytics.
Conclusions: Atypical antipsychotics can be expected to be less likely associated with antiparkinsonians. This result is indeed found for olanzapine, clozapine and to a limited extent for risperidone. Furthermore, a trend towards a positive association between atypical antipsychotics and antidepressants appears. In view of the antidepressive action of certain atypical antipsychotics, this result is surprising. The increase in the prescriptions of anxiolytics concerns all types of antipsychotics. In view of the increase in associated medications in schizophrenia and the difficulty of estimating it in randomised trials, this study underlines the contribution of naturalistic studies on this score.