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Abstract

Subthreshold hypomania is defined as a distinct period of elevated, expansive or irritable mood lasting for at least four days, but insufficient to fulfill the criteria of hypomania. This study aimed to investigate the association between suicidality and subthreshold hypomania in subjects with and without major depressive disorder (MDD).Face-to-face interviews were completed for 12,526 adults, randomly selected through a one-person-per-household method, using the Korean version of the Composite International Diagnostic Interview (K-CIDI) and a questionnaire relative to lifetime suicide attempts (LSA).Of the 12,526 participants, 11,701 did not have MDD, and 825 were diagnosed with MDD. The MDD with subthreshold hypomania group (n = 72) revealed significantly higher rates of LSA and post-traumatic stress disorder (PTSD) than those without (n = 753). Compared to the no MDD without subthreshold hypomania group (n = 11,571), the no MDD with subthreshold hypomania group (n = 130) showed a significantly higher prevalence of suicidality and comorbid conditions. In multivariate logistic regression analyses of depressive symptoms, subthreshold hypomania was significantly associated with morning worsening of mood. The MDD with subthreshold hypomania group was significantly associated with LSA (AOR=16.82, 95% CI 9.81–28.83, p< 0.001), compared to the no MDD group without subthreshold hypomania. Compared to the MDD without subthreshold hypomania group, the MDD with subthreshold hypomania group revealed a significant association with LSA (AOR=2.08, 95% CI 1.20–3.62, p< 0.001).A history of subthreshold hypomania doubled the risk of LSA in patients with MDD compared to those without subthreshold hypomania.