Collaborative care treatment for major depressive disorder.

Introduction: Major Depressive Disorder (MDD) is a burdensome behavioral health condition that is costly and difficult to treat, particularly for patients with severe cases. The Collaborative Care Model (CoCM) has been shown to be effective for moderate depression treatment but less is known about its effectiveness for severe depression. This study analyzes the impact of CoCM treatment on outcomes for depression patients across all ranges of MDD severity at Concert Health. Materials and methods: Analysis was completed utilizing all closed patient treatment episodes (N = 30,162) at Concert Health between 2018 and 2025. Of these patients, 5,693 began treatment with severe depression. We compare effect sizes for change between baseline and final screener scores across severity levels. Additionally, we utilize logistic regression to complete analyses to understand treatment factors and patient characteristics that are associated with treatment response and remission, as measured by changes in PHQ-9 scores. Results: The primary analysis showed that patients with severe depression (PHQ-9 > 20) had slightly lower odds of achieving response compared to patients with moderate depression (OR: 0.93). The treatment factors of insurance type, suicide risk, anxiety presence, and touchpoints also had significant effects on the odds of achieving response and remission. Discussion: The results suggest that CoCM may be effective for patients with severe depression in achieving treatment response. Patients on Medicaid or with more complex conditions such as anxiety presence or elevated risk for suicide may need higher levels of engagement from the care team to achieve response and remission.