PROJECT SUMMARY AND ABSTRACT – Cambridge Health Alliance ALACRITY for Early Screening and Treatment of High Risk Youth (eSToRY) R34 - Quantifying real-world effectiveness of mental health interventions for suicide prevention in at- risk adolescent and transitional age youth Identifying effective suicide prevention strategies for racial/ethnic and language (REL)-diverse populations of youth at high risk of suicide has enormous public health importance. Suicide rates for persons aged 10–24 have increased by more than 50% over the last decade in nearly every state and for nearly every racial/ethnic minority group, with particularly concerning increases in suicide attempts among Black youth. In this project, we utilize a unique clinical-sociocontextual dataset of over 15,000 youth patients at high risk for suicide to conduct high-dimensional comparative effectiveness research (CER) of community-based mental health interventions in the prevention of self-injurious thoughts and behaviors among REL-diverse adolescents and transitional age youth. We leverage an enormous warehouse of clinical, insurance, criminal justice, individual- and neighborhood-level social determinants of health data to multi-dimensionally match treatment and control groups and assess the impact of differing community-based treatment regimes on suicidal outcomes. In Aim 1, we propose innovative comparative effectiveness research using a large retrospective clinical- sociocontextual dataset to identify effective treatments for suicide prevention, and how these differ across REL-diverse groups. In Aim 2, we identify a sub-sample of this cohort in the present day, following up our retrospective analysis with a computerized adaptive test analyzing current day suicidal outcomes, psychopathology, and measures social determinants of health and quality of care. This will allow for assessment of long-run treatment outcomes, and how unobserved variables may bias comparative effectiveness research results. This study lays the groundwork for two R01-level studies: 1) a larger CER trial of treatment regimes across multiple institutions; and 2) a sequential multiple assignment randomized trial (SMART) that evaluates the impact of systematic adaptation of treatment on suicide outcomes. The project will contribute to a better understanding of whether, how, when, and for whom to alter the duration, frequency, type, or delivery of treatments at pivotal steps in the episode of treatment, leading to interventions that will reduce the risk of suicidality in vulnerable REL-diverse populations.