Randomized double blind comparison of olanzapine vs. clozapine on subjective well-being and clinical outcome in patients with schizophrenia

Objective: This randomized double-blind multicenter trial evaluated the effects of olanzapine vs. clozapine on subjective well-being, quality of life (QOL) and clinical outcome. Method: The primary objective was to demonstrate non-inferiority of olanzapine, mean dosage 16.2 ± 4.8 (5-25 mg/day) vs. clozapine, mean dosage 209 ± 91 (100-400 mg/day) regarding improvement on the 'Subjective Well-Being under Neuroleptic Treatment' (SWN) Scale after 26 treatment weeks in 114 patients with schizophrenia. Secondary outcome parameters included: Munich QOL Dimension List (MLDL), Positive and Negative Symptom Scale (PANSS), Clinical Global Impression (CGI). Results: SWN scores improved significantly in both groups, olanzapine was non-inferior to clozapine (group difference 3.2 points in favor of olanzapine; 95% CI: 4.2;10.5). MLDL-satisfaction, PANSS and CGI-S improved similarly, olanzapine yielded a higher CGI Therapeutic Index. Individual SWN and PANSS changes correlated only moderately (r = -0.45). Conclusion: Olanzapine was non-inferior to clozapine. The lack of a marked correlation between PANSS and SWN improvements indicates that patients and psychiatrists perceive treatment differently.