Predominant previous polarity as an outcome predictor in a controlled treatment trial for depression in bipolar I disorder patients

IntroductionWe hypothesized that predominant episode-polarity would predict response to treatment of depressive episodes in bipolar I disorder (BPD) patients with treatment in a placebo-controlled trial, in the sense that patients with manic predominant polarity (PM) would respond better than patients with depressive predominant polarity (PD).MethodThis post-hoc analysis of a published trial examined outcomes of 788 depressed (MADRS score ≥ 20) adult BPD patients with baseline and follow-up assessments, according to their predominant polarity based on previous recurrences of mania-hypomania vs. depression in ≥ 2:1 excess. Patients (total = 833) were randomized to an 8-week trial of treatment with placebo (n = 377), olanzapine (5-20 mg/day; n = 370), or olanzapine/fluoxetine combination (OFC; 6/25, 6/50, or 12/50 mg/day; n = 86). Treatment response was based on improvement in Clinical Global Impression of depression severity (CGI-D). We analyzed for associations of this outcome with predominant lifetime illness-polarity, based on retrospective SCID-based assessment of individual clinical history.ResultsPredominant polarity could be demonstrated in 367/788 patients (46.6%), showing a 2.7-fold excess of predominant depressive over manic past-illnesses (34.1%/12.4%), with similar distribution by sex and among treatment-arms. Moreover, based on least-square change in CGI-D severity (based on a mixed model of repeated measures [MMRM]), predominant polarity has different impact in the treatment outcome for each gender. Men with predominantly manic polarity had statistically significant better improvement than men with predominantly depressive polarity. Such difference was not observed in the female population. Other outcome measures yielded similar conclusions.ConclusionsPredominant previous depressive > manic episodes selectively yielded poorer responses of BPD to treatment for acute BP depression, particularly in men.