Stratified-Care School-Based Intervention for Adolescent Suicidal Ideation

Suicide among adolescents and young people is a highly prevalent global issue, with suicidal ideation reaching rates of approximately 18% and suicide attempts around 6% (1). According to the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD), suicide ranks as the fifth leading cause of death among individuals aged 10 to 24 (2), with a mortality rate of 6.0 per 100,000 in this age group (3). Suicide mortality increases with age: 1.2 per 100,000 among those aged 10-14; 6.7 among those aged 15-19; and 10.6 among those aged 20-24 (3). In Latin America, suicide mortality rates surpass global averages, reaching 9.8 per 100,000, and in Chile, the rate is 7.2 per 100,000 (3).

Numerous risk factors are associated with suicide, including genetic, biological, psychological, and social factors (4,5). Each case of suicide is caused by a unique, dynamic, and complex interaction of these elements (4,5). However, depression remains the most frequently reported common factor (4). A recent literature review found that between 50-65% of suicide cases met criteria for depression (4). Regarding its broader impact, depressive symptoms are even more prevalent than suicidal ideation, with global rates of 43.9%, including mild, moderate, and severe cases (6). Moreover, the number of depression cases among adolescents has grown exponentially, with a 21.6% increase in total cases and a 19% increase in incidence compared to the 1990s (7). In Chile, adolescent depression is estimated to affect 8.3% of the population, yet fewer than half receive mental health care (8).

Secondary schools are recognized as appropriate, accessible, and effective settings for suicide (9) and depression prevention programs (10) for adolescents. School-based interventions offer broad reach and enable large-scale prevention efforts (9,10). Evidence shows that such programs improve suicide awareness and coping skills to reduce suicidal thoughts and attempts (9,11,12). However, indicated interventions-those targeting at-risk individuals with clinical or psychosocial approaches such as cognitive-behavioral therapy (CBT)-remain less common in school settings (13), despite their established efficacy in other contexts (13), underscoring the need for further research on their implementation in schools.

Two CBT-based programs have demonstrated effectiveness and safety in reducing suicidal ideation and depressive symptoms. Both are indicated interventions, meaning they target individuals already at risk and are delivered individually.

The Reframe-IT program, developed in Australia, targets behavioral activation, cognitive restructuring, emotion regulation, stress tolerance, and problem-solving skills (14). It includes eight digital sessions designed for delivery by school well-being staff (14). A pilot randomized controlled trial in Australia showed greater reductions in suicidal ideation, depression, and hopelessness among the intervention group than controls, although differences were not statistically significant due to insufficient statistical power (14). In Chile, the research team collaborated with the University of Talca for over four years to culturally adapt Reframe-IT, developing Reframe-IT+ by adding five face-to-face sessions to the original eight. An initial pilot study with 52 participants showed high acceptability and reductions of 15.2 points in suicidal ideation and 3.5 in depressive symptoms (15). A subsequent RCT with 1,546 screened students and 100 randomized participants demonstrated significant decreases of 6.7 points in suicidal ideation and 3.1 in depressive symptoms (16). Following these positive results, a scaled-up quasi-experimental study in Santiago (CEC2024061) included 75 students and showed preliminary reductions of 2.5 points in suicidal ideation and 3.2 in depressive symptoms.

The CARIBOU program, developed in Canada, targets behavioral activation, cognitive restructuring, problem-solving, and communication skills (17). It consists of 16 sessions facilitated by trained professionals from diverse backgrounds. A non-randomized pilot study showed a 2-point reduction in depressive symptoms (17). Moreover, 80% of participants reported program engagement, and facilitators achieved 95% fidelity in implementation (17). The research team has initiated contact with Dr. Darren Courtney, CARIBOU's lead developer, to begin its cultural adaptation in Chile as part of the present study.

This study proposes a stratified-care intervention model in which treatment intensity is matched to individual needs, ensuring appropriate levels of care. Adolescents with suicidal ideation will be offered Reframe-IT+ if they present with mild or moderate depressive symptoms, and CARIBOU if they present with severe symptoms.

METHODOLOGY General Objective The general objective of this study is to examine the acceptability of the CARIBOU program and the feasibility and fidelity of implementing a stratified-care approach tailored to the needs of adolescents with suicidal ideation. Under this model, students with mild or moderate depressive symptoms (PHQ-9 \< 20) will be offered the Reframe-IT+ program, and those with severe depressive symptoms (PHQ-9 ≥ 20) will be offered the CARIBOU program. Additionally, this study aims to explore the efficacy of a stratified-care intervention in adolescents at risk for suicide and with depressive symptomatology.

• Suicidal ideation [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months.]
• Suicidal ideation frecuency [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months.]
• Depressive symptoms [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months.]
• Anxiety symptoms [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months.]
• Hopelessness [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months.]
• Mood [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months.]
• Psychotic symptomatology [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months.]
• Impairment [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months]
• Behavioral Activation [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months]
• Problem-solving [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months]
• Emotion regulation [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months]
• Wellbeing and quality of life [Time frame: pre-post assessments and follow-ups at 3, 6, 9, and 12 months]