Bipolar Disorder Type I Associated With Worse Depression Course Than Type II

Published in Bipolar Disorders, results from a clinical study identified 4 distinct trajectories of depressive symptoms among individuals with bipolar disorder. Patients with bipolar type I were more likely to experience a worse trajectory compared with patients with bipolar type II.

Data were abstracted from the Bipolar Clinical Health Outcomes Initiative in Comparative Effectiveness (CHOICE) trial, a 6-month randomized controlled trial that assessed the relative efficacy of lithium and quetiapine treatment among 482 adult patients with bipolar disorder type I (68.3%) or type II (31.7%). The study was conducted across 11 sites in the United States over the course of 3 years (2010-2013). At study entry, patients provided sociodemographic and clinical information to research coordinators. Bipolar disorder symptomatology was monitored at baseline and across 8 follow-up visits over the study course. Depressive symptoms were assessed per the Montgomery-Asberg Depression Rating Scale; remission was defined as a score ≤12 at the conclusion of follow-up. Growth Mixture Modeling was used to identify depressive symptom trajectories among patients.

Four depressive symptom trajectories were identified among participants. The responding class (60.3%) was characterized by a rapid reduction in symptoms and subsequent maintenance of low depression symptomatology. The partial-responding class (18.4%) experienced an initial symptom reduction followed by an increase during the remaining weeks. The fluctuating class (11.6%) experienced a fluctuation in depressive symptoms across the study course, whereas the nonresponding class (9.7%) displayed sustained moderate to severe depressive symptoms throughout follow-up. Bipolar type I predicted membership in the nonresponding class, and random assignment to quetiapine predicted membership in either the responding class or the nonresponding class.

The responding and fluctuating classes had the highest proportion of patients in remission at the end of the follow-up period, at 95.9% and 52.5%, respectively. Just 15.9% of partial-responders experienced remission compared with no individuals in the nonresponding group. In addition, an average 7% increase in Montgomery-Asberg Depression Rating Scale score from baseline to week 24 was reported for the nonresponding group. According to multivariable analysis, patients with bipolar disorder type I (vs type II) had 3-fold greater odds of membership in the nonresponding class compared with the responding class (P =.04). In addition, patients randomly assigned to quetiapine treatment compared with patients randomly assigned to lithium had higher odds of membership in the responding class compared with the nonresponding class (P =.023).

These data suggest that depression trajectory may be more severe among patients with bipolar disorder type I compared with bipolar disorder type II. Although no differences in overall outcome were observed between treatment groups, patients who received lithium had a more variable trajectory. Further research should investigate the specific factors that may affect treatment response and subsequent outcome in depressive symptoms.

Reference

Behrendt-Møller I, Madsen T, Sørensen HJ. Patterns of changes in bipolar depressive symptoms revealed by trajectory analysis among 482 patients with bipolar disorder [published online November 1, 2018]. Bipolar Disord. doi: 10.1111/bdi.12715