Research suggests that there are significant interactions between mental illness and chronic medical conditions, with greater morbidity, cost and poorer outcomes, both for the chronic medical disorder and for the mental illness in persons with both conditions. This analytic epidemiologic study aims to further scientific knowledge about the effectiveness and outcomes of treatments for both diabetes and behavioral health disorders, including depression, serious and persistent mental illness (SPMI) and substance abuse, when these conditions co-exist in Mainers served by the publicly funded health and mental health systems. The project will provide data to clarify how co-existing mental illness and chronic medical disorders modify the utilization and comparative effectiveness of proven prevention and treatment interventions for each condition and the impact of these co-morbidities on overall health and disease specific outcomes in these complex populations. This study will lay the foundation for Maine's efforts to identify and implement more effective, integrated and person centered interventions to promote the overall health and safety of the complex individuals in the state's publicly funded health and human service system. Based on diagnoses on two years of Medicaid services claims, all 18-64 year old Medicaid members with continuous eligibility and full benefits will be assigned to one of three cohorts, a group with mental illness diagnoses, but no substance abuse;a group with both mental illness and substance abuse;and a group with neither behavioral health diagnosis. The mental illness groups will be further subdivided into subgroups with SPMI or depression. These cohorts will be further subdivided by the presence of diabetes. The index cohorts will be as follows: SPMI and diabetes, depression and diabetes and dual diagnosis depression or SPMI and diabetes. The cohorts with mental illness only, diabetes only and neither mental illness nor diabetes will be comparison groups. Utilization of prevention and treatment interventions, quality metrics and outcomes, defined in AHRQ publications, will be compared among the different cohorts. Where none exist, novel metrics will be created to categorize behavioral health interventions;by examining which of these are associated with better outcomes, the project will add to the evidence base on behavioral health quality interventions and metrics. Analyses will be bi- directional, examining the impact of mental illness on the utilization, quality, effectiveness of interventions, cost and outcome for diabetes, as well as the impact of diabetes and other medical co-morbidities on utilization, cost and outcome in the groups with mental illness. The findings of this project are expected to lay a foundation for future research on strategies that improve the health of complex individuals and promote the integration of mental and physical health in our traditionally separate mental, physical and public health systems of care. PUBLIC HEALTH RELEVANCE: This project will add to the evidence base about which interventions, or combinations of interventions, will best promote better outcomes for individuals with complex combination of multiple chronic conditions. Groups that have barriers in accessing otherwise effective intervention services will be identified, and enhanced outreach or adaptations of existing interventions can then be targeted to these health disparities groups. The knowledge gained will promote transformation of our health delivery system such that health issues are integrated into mental health systems of care and mental health better represented in health policy and programming of our traditional health care and public health systems. The project will further the development of tools, especially in behavioral health, to measure outcomes and the quality of the care that complex patients with multiple co- morbidities receive. These tools are essential to the development of quality improvement programs that address the overuse, underuse and misuse of both mental and physical health care interventions.