¹Kyung Hee University, Psychiatry, Seoul, Korea, Republic of, ²Kongju National University, Health Administration, Kongju, Korea, Republic of, ³CHA Ilsan Medical Center, Psychiatry, Goyang, Korea, Republic of, ⁴Yale School of Medicine, Psychiatry, New Haven, United States, ⁵Soonchunhyang University, Psychiatry, Cheonan, Korea, Republic of

Background: South Korea maintains the highest suicide rate in the OECD despite ongoing prevention efforts. Major depressive disorder (MDD) is the leading diagnosis among suicide deaths, yet evidence for effective psychosocial interventions for suicidal ideation remains limited.

Aims & Objectives: This study evaluated the effectiveness of a structured, hospital-based case management programme in reducing suicidal ideation and associated clinical outcomes among patients with MDD at suicidal risk.

Method: ​In this six-centre, assessor-blinded, randomised controlled trial, adults with MDD and current suicidal ideation or a recent attempt were recruited from psychiatric outpatient clinics. in South Korea. Participants were randomly assigned (1:1) to receive either 6 months of assertive case management (ACM: n = 158) or usual care (EUC: n = 156). ACM involved manualised, four-phase psychosocial case management delivered by trained case managers under psychiatric supervision. The primary outcome was the change in Columbia–Suicide Severity Rating Scale (C-SSRS) total score from baseline to 6 months. Secondary outcomes included depression, suicidal intent and ideation, anxiety, loneliness, impulsivity, quality of life, and service utilisation.

Results: Between March 2019 and November 2022, 314 participants were enroled (158 ACM, 156 EUC), and 245 (132 ACM, 113 EUC) completed the 6-month follow-up. The ACM group showed a significantly greater mean reduction in C-SSRS total score than the EUC group (−9·22 vs −7·23; adjusted mean difference −1·99 [95% CI −3·37 to −0·61]; p = 0·0046). Greater improvements were also observed in the ACM group for depressive symptoms (HAM-D: −9·19 vs −6·23; p = 0·0027), suicidal ideation (BSSI: −7·96 vs −5·58; p = 0·0145), and anxiety (GAD-7: −3·90 vs −1·85; p = 0·0017). There were no significant between-group differences in suicide attempts, and one suicide occurred in the control group.

Discussion & Conclusions: Structured, hospital-based case management resulted in greater reductions in suicidal ideation and depressive symptoms than usual care. These findings support implementing psychosocial case management as a scalable component of hospital-based suicide prevention. Further research should assess long-term effects and broader implementation.