Long-term treatment response to continuous cycling course in bipolar disorders: A meta-analysis

Objective: About 30% of patients with bipolar disorders (BD) exhibit a continuous cycling course (CCC). These patients significantly differ from those with non-continuous cycling course (N–CCC) on clinical presentation and have a poorer short-term response to antidepressant treatment. Our aim is to conduct a meta-analysis of the studies comparing long-term treatment response in CCC and N–CCC bipolar patients. Method: We conducted a systematic review of studies on patients with a diagnosis of bipolar disorder with CCC. Our primary outcome measure was the response to treatment at the last follow-up visit. The data analysis was based on the success rate difference as the effect size measure. To account for heterogeneity of primary studies, aggregation of results was based on a random-effects model. Results: We included six observational studies comprising a total of 671 patients (CCC 29.4%, N–CCC 70.6%). Overall, the response rate was 34.0% in the CCC and 49.3% in the N–CCC arm. The meta-analysis shows a significant association between cycle pattern and response (success rate difference: −0.17; 95% CI: −0.25, −0.09; p < 0.0001), with low heterogeneity (χ2 (5)= 5.16; I2 = 3%). Conclusion: In bipolar disorders, patients with CCC have a poorer response to prophylactic treatment compared with patients with N–CCC.