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Olanzapine more effective for patients with lower bipolar I disorder symptom severity

Lower baseline symptom severity was associated with greater treatment response to olanzapine among patients with bipolar I disorder.

“Results from some studies suggested that antidepressants might be less efficacious for the milder spectrum of the disorder compared with placebo, whereas others did not, leading to considerable debate among scientists and alarmist headlines in public newspapers. The effect of this media attention on patients’ adherence to prescribed medications is still unknown but, in view of the extensive media coverage of the topic, it is unlikely to be negligible,” Myrto T. Samara, MD, of Universität München, Munich, and colleagues wrote.

To assess the effect of baseline symptom severity on the efficacy of olanzapine for bipolar I disorder, researchers conducted an individual participant data meta-analysis of double-blind, randomized, controlled trials comparing olanzapine with placebo. Analysis included five reports with data for 939 patients: 552 who received olanzapine and 387 who received placebo.

Baseline severity and treatment were significantly associated (P = .013). As baseline severity increased, differences between olanzapine and placebo increased.

Both treatment groups exhibited decreases in mean estimated Young Mania Rating Scale scores at 3 weeks. However, decreases were greater among participants who received olanzapine by 2.56 points for those with a baseline score of 20 to 25; by 4.74 points for those with a baseline score of 25 to 35; and by 8.01 points for those with a baseline score of 35 to 60, compared with placebo.

“These results showed that olanzapine is efficacious for the treatment of acute manic or mixed episodes across the initial symptom severity spectrum. Nevertheless, the difference in symptom improvement between olanzapine and placebo increased as the baseline severity increased,” the researchers wrote. “Clinicians should weigh up the benefits and risks of treatment with olanzapine, and this is particularly important towards the mildest end of baseline severity range. Clinicians should also take into account the potential prophylactic effect of olanzapine in the long term.” – by Amanda Oldt

Disclosures: Samara reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.