Prevalence of Lifetime Psychiatric Disorders and Suicidality in Adults With Subthreshold Posttraumatic Stress Disorder: A Population-Based Nationwide Study in Korea

Background: Subthreshold posttraumatic stress disorder (PTSD) is a chronic condition, and despite its clinical importance, few studies have been conducted. We investigated the relationship of subthreshold PTSD with various psychiatric disorders and suicidality in a South Korean general population. Method: A total of 5,102 respondents, aged at least 18 years, completed face-to-face interviews using the Korean version of the Composite International Diagnostic Interview and questionnaires for lifetime suicidal ideation, plans, and attempts. Subthreshold PTSD was defined as at least one symptom in each of the three symptom clusters (Criteria B, C, and D) and a symptom duration of >= 1 month (Criterion E). Results: The lifetime prevalence of subthreshold PTSD (2.5%) was higher than that of PTSD (1.5%). After adjusting for sociodemographic factors, subthreshold PTSD was significantly associated with nicotine use disorders, major depressive disorder, obsessive-compulsive disorder (OCD), generalized anxiety disorder, and specific phobia. Among psychiatric disorders, the odds ratio for OCD was notably high. Subthreshold PTSD was associated with increased suicidal ideation (adjusted OR [AOR] = 2.90, 95% CI [1.98, 4.26]), suicidal plans (AOR = 3.58, [1.86, 6.89]), and suicide attempts (AOR = 3.93, [1.93, 8.01]) after adjusting for sociodemographic factors. When adjusted for sociodemographic factors and psychiatric disorders, suicidal ideation (AOR = 2.04, [1.34, 3.11]) remained statistically significant. Conclusion: This study found that subthreshold PTSD was associated with various psychiatric disorders and suicidality. Increased attention to the mental health of individuals with subthreshold PTSD is necessary. Clinical Impact Statement The prevalence of subthreshold posttraumatic stress disorder (PTSD) is higher than that of PTSD, and subthreshold PTSD is associated with various psychiatric disorders and suicidality. However, subthreshold PTSD can be overlooked in clinical settings because it is studied less often and individuals with subthreshold PTSD are less likely to be aware of the symptoms. Therefore, considering the high suicidal risk of individuals with subthreshold PTSD in this study, we suggest that clinicians and policy makers should pay attention to the mental health of individuals with subthreshold PTSD.