Long-term Effects of a Collaborative Care Model on Metabolic Outcomes and Depressive Symptoms: 36-Month Outcomes from the INDEPENDENT Intervention

Abstract

Background: Collaborative care (CC) is a multicomponent team-based approach to providing mental health care with systematic integration into outpatient medical settings. The 12-month INDEPENDENT CC intervention improved joint disease control measures in patients with both depression and diabetes at 12 and 24 months following randomization. Objective: This study investigated the durability of intervention effects on patient outcomes at 36 months following randomization. Participants: Adult patients with poorly controlled T2D and depression in India randomized to CC or usual care. Design: Post hoc analyses of between-group differences in patient outcomes at 36 months post-randomization (N = 331) and maintenance of outcomes from 12 to 36 months (N = 314). Main measures: We evaluated combined risk factor improvement since baseline, defined as ≥ 50.0% reduction in Symptom Checklist Depression Scale (SCL-20) scores along with reduction of at least 0.5 percentage point hemoglobin A1C, 5 mmHg systolic blood pressure, or 10 mg/dL low-density lipoprotein cholesterol. Improvements in single risk factors were also examined. Key results: There were no between-group differences in improvements since baseline in multiple or single risk factors at 36 months. Patients in the CC group with improved outcomes at 12 months were more likely to maintain a ≥ 50.0% reduction since baseline in SCL-20 scores (CC [54.9%] vs. UC [40.9%]; RR: 1.27 [95% CI: 1.04, 1.56]) and 0.5 percentage point reduction since baseline in hemoglobin A1C (CC [31.9%] vs. UC [19.5%]; RR: 1.64 [95% CI: 1.11, 2.41]) at 36 months. Conclusions: While improvements since baseline in patient outcomes did not differ between the collaborative care and usual care groups at 36 months, patients who received CC were more likely to maintain improvements in depressive symptoms and glucose levels at 36 months if they had achieved these improvements at the end of active intervention.