Olanzapine and Olanzapine-Fluoxetine Combination Treatment and Bipolar I Depression

We read with great interest the article by Tohen et al¹ “Efficacy of Olanzapine and Olanzapine-Fluoxetine Combination in the Treatment of Bipolar I Depression.” We also attended a presentation at the 2003 American Psychiatric Association Annual Meeting² when the same study was presented and notice rather strangely that the remission rates of the study on both occasions were different even though the study population was the same. At the American Psychiatric Association meeting, the remission rates quoted were placebo, 29.1%; olanzapine, 40.5%; and olanzapine-fluoxetine combination, 56.3%. On the other hand, in the November article, the rates quoted were placebo, 24.5%; olanzapine, 32.8%; and olanzapine-fluoxetine combination, 48.8%. Could the authors please explain the reason(s) for the disparities?

From a methodological viewpoint, the design of the study could be faulted on the basis of being an incomplete factorial design. The addition of a fluoxetine monotherapy arm would have completed the design.

Correspondence: Dr Williams, Department of Psychiatry, University of Illinois at Chicago, 912 S Wood St, Chicago, Il 60612 (awilliams@psych.uic.edu).