Effects of venlafaxine versus lithium monotherapy on quality of life in bipolar II major depressive disorder: Findings from a double-blind randomized controlled trial

Bipolar disorder is associated with decreased quality of life, especially during depressive episodes. There are few studies that have examined whether quality of life improves following pharmacological treatments of bipolar depression. In this exploratory study, we examined the effects of antidepressant versus mood stabilizer mono therapy on quality of life ratings in bipolar II subjects during acute (12 week) treatment. Data were derived from a randomized double-blind comparison of venlafaxine (n = 65) versus lithium (n = 64) monotherapy. The Quality of Life Index (QLI) was administered at baseline (n = 126; 98%) and again at the end of treatment. We explored treatment differences in continuous changes on the QLI using last-observation carried forward. Additionally, we explored the likelihood of experiencing clinically-significant improvements as well as baseline correlates of QLI and changes in QLIe. Venlafaxine was superior to lithium in reducing symptoms of depression during acute treatment. However, there were no significant differences between treatments in QLI ratings. Changes in symptoms of depression were correlated to, but not redundant, with improvements in QLI ratings. These findings suggest that quality of life may be an important secondary outcome to target and measure as a part of comparative clinical trials of pharmacotherapy for bipolar II depression.