Effect of Prior Depression Diagnosis on Bipolar Disorder Outcomes: A Retrospective Cohort Study
This retrospective cohort study analyzed 5,595 Japanese patients newly diagnosed with bipolar disorder to examine whether a prior depression diagnosis and its duration affected psychiatric and all-cause hospitalization rates and mortality. Patients with prior depression history showed slightly lower all-cause hospitalization risk (HR=0.87), with duration of preceding depression (≥1 year vs <1 year) not significantly altering psychiatric hospitalization outcomes.