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

•Among 592 patients with bipolar depression, initial non-response was high.•Among patients with non-response after 6 weeks, only one-third eventually responded by 24 weeks.•The findings did not improve among patients with additional guideline-based treatment. We aimed to study the probability of bipolar depression response at 24 weeks given initial non-response. 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