Response and remission rates during 24 weeks of mood-stabilizing treatment for bipolar depression depending on early non-response.

Background: We aimed to study the probability of bipolar depression response at 24 weeks given initial non-response.

Methods: We combined two multi-site, 24-week trials including similar populations following the same evidence-based guidelines randomizing patients to lithium or quetiapine. Additional mood-stabilizing treatment was possible if clinically indicated. We report cumulative proportions of response (>50% improvement in MADRS) and remission (MADRS<10).

Results: We included 592 participants with bipolar depression (mean 39 years, 59% female, mean MADRS 25). Among 393 (66%) participants without response after 2 weeks, 46% responded by 24 weeks; for 291 (49%) without response at 4 weeks, 40% responded and 33% remitted by 24 weeks; for 222 (38%) without a response at 6 weeks, 36% responded and 29% remitted by 24 weeks; for 185 (31%) without a response at 8 weeks, 29% responded and 24% remitted by 24 weeks. Rates were similar for participants who had started an additional mood-stabilizing drug during the first 6 or 8 weeks.

Conclusions: Among patients with bipolar depression and non-response after 6 weeks treatment, representing an adequate bipolar depression trial, only one-third responded by 24 weeks. These results highlight the need for better treatment alternatives for non-responders to evidence-based treatments for bipolar depression.