Efficacy and mood conversion rate during long-term fluoxetine v. lithium monotherapy in rapid- and non-rapid-cycling bipolar II disorder

Background Controversy exists over antidepressant use in rapid-cycling bipolar disorder. Aims Exploratory analysis of safety and efficacy of fluoxetine v. lithium monotherapy in individuals with rapid- v. non-rapid-cycling bipolar II disorder. Method Randomised, double-blind, placebo-controlled comparison of fluoxetine v. lithium monotherapy in patients initially stabilised on fluoxetine monotherapy (trial registration NCT00044616). Results The proportion of participants with depressive relapse was similar between the rapid- and non-rapid-cycling groups (P=0.20). The odds of relapse were similar between groups (P=0.36). The hazard of relapse was similar between groups (hazard ratio 0.87, 95% CI 0.40-1.91). Change in mania rating scores was similar between groups (P=0.86). There was no difference between groups in the rate of syndromal (P=0.27) or subsyndromal (P=0.82) hypomania. Conclusions Depressive relapse and treatment-emergent mood conversion episode rates were similar for lithium and fluoxetine monotherapy and placebo during long-term, relapse-prevention therapy of rapid- and non-rapid-cycling bipolar II disorder.