Objective: Risperidone and olanzapine are the 2 most widely prescribed second-generation antipsychotics. The purpose of this study was to compare the efficacy of risperidone and olanzapine using duration of hospitalization as the primary outcome measure. This outcome was selected as it is an indirect measure of how well patients are responding to the medication and represents a "real world" endpoint relevant to practicing hospital psychiatrists.

Method: The study was done at a large state psychiatric hospital in North Carolina from 2001 to 2003. Subjects were eligible for inclusion if they required treatment with an antipsychotic (e.g., positive symptoms) and were able to provide informed consent. Eighty-five patients entered the study and were randomly assigned to risperidone (N = 40) or olanzapine (N = 45) as their initial antipsychotic. Treatment was naturalistic, and dosing was based on the discretion of the treating physician.

Results: There was no significant difference in the mean durations of hospitalization for the risperidone group (7.9 days) as compared to the olanzapine group (8.1 days). There were no significant differences in the demographics of either treatment group, but, during the study, risperidone-treated patients used more antihistamines (chi² = 4.0, p = .05). Eighty percent of each group (N = 36, olanzapine; N = 32, risperidone) remained on the study medication at discharge.

Conclusions: Risperidone and olanzapine were equally efficacious, suggesting that measures other than "efficacy" (e.g., side effects, cost) should be considered when determining overall "effectiveness" of treatment.