Hospital-Based Psychosocial Case Management and Suicide Prevention in South Korea: A Randomized Clinical Trial.

Importance: South Korea maintains the highest suicide rate in the Organization for Economic Cooperation and Development, with major depressive disorder (MDD) being the leading diagnosis among suicide deaths. Evidence from large-scale randomized clinical trials (RCTs) is limited, particularly for diagnosis-specific, long-term programs in outpatient settings. Objective: To evaluate the effectiveness of a structured, hospital-based case management program in reducing suicidal ideation and associated clinical outcomes among patients with MDD. Design, Setting, and Participants: This RCT was conducted at 6 general hospitals in South Korea from January 18, 2021, to July 31, 2024. Participants included outpatients 18 years or older with MDD who had current suicidal ideation or a suicide attempt within the past 2 months. All efficacy analyses were performed according to the intention-to-treat principle. Intervention: Participants were randomized 1:1 to receive either 6 months of structured assertive case management (ACM) as an adjunct to standard treatment (n = 158) or usual psychiatric care alone (control [n = 156]). Main Outcomes and Measures: The primary outcome was the change from baseline to 6 months in the overall severity of suicidal thoughts and behaviors (STBs), as assessed by the Columbia-Suicide Severity Rating Scale (C-SSRS). Secondary outcomes included changes in depression, suicidal intent and ideation, anxiety, loneliness, impulsivity, quality of life, and service utilization. Results: Of 314 participants enrolled (mean [SD] age, 32.3 [13.1] years; 207 [65.9%] female), 158 were randomized to the ACM group and 156 to the control group; 245 (132 in the ACM and 113 in the control groups) completed the 6-month follow-up. The ACM group showed a significantly greater mean (SD) reduction in C-SSRS total score than the control group (-9.22 [0.49] vs -7.23 [0.50]; adjusted mean difference, -1.99 [95% CI, -3.37 to -0.61]; P = .005). Greater mean improvements were also observed in the ACM group for depressive symptoms (Hamilton Depression Rating Scale mean [SD] change, -9.19 [0.70] vs -6.23 [0.69]; P = .003), suicidal ideation (Beck Scale for Suicidal Ideation mean [SD] change, -7.96 [0.62] vs -5.58 [0.75]; P = .01), and anxiety (Generalized Anxiety Disorder-7 mean [SD] change, -3.90 [0.44] vs -1.85 [0.48]; P = .002). No significant between-group differences were observed in suicide attempts, and 1 suicide death occurred in the control group. Conclusions and Relevance: In this RCT of outpatients with MDD and high suicide risk, ACM significantly reduced C-SSRS total scores and psychological distress compared with usual care. These findings provide a critical, high-level evidence base for the national implementation of standardized, hospital-centered psychosocial interventions as a scalable public health strategy for suicide prevention. Trial Registration: Clinical Research Information Service Identifier: KCT0008123.