INTRODUCTION: Antipsychotic treatment dose adjustments may influence treatment outcomes in patients with schizophrenia. METHODS: We analysed data from 4,247 outpatients with schizophrenia who started olanzapine monotherapy in the 3-year, prospective, observational SOHO study to determine factors associated with olanzapine dose adjustments and how these impact on treatment effectiveness and tolerability. RESULTS: Regression analyses showed an association between changes in the Clinical Global Impression (CGI) and olanzapine dose changes: patients with a lack of effectiveness were more likely to have their dose increased, whereas patients with good treatment response were more likely to have a dose decrease. Improvement in tardive dyskinesia was associated with dose increase or no change (p=0.034) and worsening of sexual problems was associated with dose decrease (p=0.001). Conversely, an increase in olanzapine dose was associated with subsequent clinical improvement (CGI), but dose adjustment had no significant effects on tolerability outcomes. DISCUSSION: These results indicate that psychiatrists tend to modify olanzapine dose according to treatment response. Dose increases seem to be associated with a better response to treatment and not with a worsening of side-effects.
