Types of Co-existing Chronic Physical Conditions and Newly-diagnosed Depression, its Treatment and Economic Outcomes among Medicaid Beneficiaries with Type 2 Diabetes

Diabetes is a widely prevalent metabolic condition. Adults with type 2 diabetes mellitus (T2DM) also have many coexisting chronic physical conditions. Coexisting chronic physical conditions among individuals with T2DM may be concordant (conditions that overlap with T2DM in their pathogenesis and management plans such as cardiovascular diseases) or discordant (conditions with unrelated pathogenesis or management plans such as musculoskeletal disorders) or dominant (conditions whose severity eclipses all other illness management plans such as metastatic cancer). There is documented evidence on the negative consequences of depression in adults with T2DM. However, there is only limited knowledge on how the types of coexisting chronic physical conditions (defined as concordant, discordant or dominant conditions) influence the risk for developing depression, subsequent depression treatment patterns and economic consequences of depression treatment, among adults with T2DM. Therefore the aims of this dissertation were to examine (1) the association of risk of newly-diagnosed depression with types of coexisting chronic physical conditions among adults with T2DM (2) the association between types of coexisting chronic physical conditions and depression treatment among adults with T2DM and newly-diagnosed depression was analyzed and (3) whether the relationship between depression treatment and total and T2DM-related healthcare care expenditures vary by types of coexisting chronic physical conditions among non-elderly adult Medicaid beneficiaries with T2DM and newly-diagnosed depression. A retrospective longitudinal cohort study design was used. Patient-level data were obtained from multi-year, multi-state Medicaid claims. Non-elderly (ages 18-64), fee-for-service Medicaid beneficiaries with T2DM who were depression free were followed for a period of 12 months to identify newly-diagnosed depression. The final study population consisted of 59,857 Medicaid beneficiaries of whom N=5,974 had newly diagnosed depression. After controlling for other risk factors, those with dominant conditions were at 17% higher risk (p=0.0006) and those with both concordant and discordant conditions were found to be at 30% higher risk (p\u3c.0001) to develop newly-diagnosed depression as compared to those with concordant conditions only. Individuals with dominant conditions (p\u3c0.05) were less likely to receive depression treatment with only antidepressants compared to those with discordant conditions only. Individuals with dominant conditions were more likely to receive depression treatment with only psychotherapy (p\u3c.01) as compared to those with discordant conditions only. No statistically significant associations were observed between types of coexisting chronic physical conditions and receipt of adequate depression treatment. As compared to no depression treatment, treating depression reduced total healthcare expenditures. As compared to no depression treatment, treatment with only antidepressants was associated with 17% reduction in total healthcare expenditures, treatment with only psychotherapy was associated with 22% reduction in total healthcare expenditures and treatment with both antidepressants and psychotherapy was associated with 28% reductions in total healthcare expenditures. As compared to no depression treatment, treatment with both antidepressants and psychotherapy was associated with reductions in total healthcare expenditures among all types of coexisting chronic physical condition groups. In summary, these results indicate that among adults with T2DM, newly-diagnosed depression rates, its treatment and economic benefits vary by types of coexisting chronic physical conditions