Prediction of major depressive episodes and suicide-related ideation over a 3-year interval among Japanese undergraduates

Background: Suicide has been a leading cause of death among young adult populations in Japan. The aim of this study was to predict major depressive episodes (MDEs) and suicide-related ideation among university students using the Patient Health Questionnaire-9 (PHQ-9) and the Temperament and Character Inventory (TCI). Methods: The subjects were 2194 university students who completed the PHQ-9 and TCI in the 1st year (T1) and the PHQ-9 in the 4th year (T2) of university. Multiple logistic regression analysis was performed to predict MDEs and suicide-related ideation at T2. Moreover, recursive partitioning analyses were conducted to reveal the future risk of MDEs and suicide-related ideation. Results: The multiple logistic regression analyses of MDEs and suicide-related ideation at T2 revealed that depressive episodes, suicide-related ideation, and low self-directedness(SD) scores at T1 were significant predictors. The area under the curve of the model for MDEs was 0.858 and that for suicide-related ideation was 0.741. The recursive partitioning analyses revealed that a PHQ-9 summary score ≥15 at T1 predicted a high risk of MDEs at T2 and that both a PHQ-9 summary score ≥5 and a PHQ-9 #9 score ≥1 predicted a high risk of suicide-related ideation at T2. Conclusions: MDEs, suicide-related ideation, and low SD scores are significant predictors of future MDEs and suicide-related ideation.