Subthreshold lifetime depression and anxiety are associated with increased lifetime suicide attempts: A Korean nationwide study

Subthreshold depression and anxiety are highly prevalent and known to be associated with functional limitations and future onset of major depression or anxiety disorders. However, studies regarding suicidality at subthreshold levels of depression and anxiety are limited. A total of 17,639 Koreans aged from 18 to 64 responded to the Korean version of the WHO-composite international diagnostic interview (K-CIDI) version 2.1 between 2006 and 2016. Prevalence of subthreshold depression and anxiety, and information on lifetime suicide attempt (SA) were assessed. Multivariable logistic regression was performed to calculate the risk of SA by the level of depression or anxiety. The risk of lifetime SA increased incrementally according to the level of depression and anxiety. In the subthreshold depression group, individuals with subthreshold anxiety increased the odds about threefold (OR = 3.15, 95% CI 3.12–3.18) and the threshold anxiety disorder group increased the odds about fivefold (OR = 5.33, 95% CI 5.27–5.38) for SA, compared to the group without any level of anxiety. In threshold depressive disorder, the subthreshold anxiety group showed about 1.8-fold higher odds (OR = 1.76, 95% CI 1.75–1.77) and the threshold anxiety disorder group showed threefold higher odds (OR = 2.93, 95% CI 2.92–2.95) for SA compared to the group without any level of anxiety. Subthreshold levels of depression and anxiety were prevalent among Koreans and were associated with an increased prevalence of lifetime SA. A detailed assessment of depression and anxiety symptoms according to their level should be performed on a diagnostic continuum to prevent suicide.