The Impact of a Collaborative Care Model on Health Trajectories among Patients with Co-Morbid Depression and Diabetes: The INDEPENDENT Study.

Context: Collaborative care models for depression have been successful in a variety of settings, but their success may differ by patient engagement. We conducted a post-hoc analysis of the INDEPENDENT trial to investigate the role of differential engagement of participants on health outcomes over 3 years.

Settings And Design: INDEPENDENT study was a parallel, single-blinded, randomised clinical trial conducted at four socio-economically diverse clinics in India. Participants were randomised to receive either active collaborative care or usual care for 12 months and followed up for 24 months.

Method: We grouped intervention participants by engagement, defined as moderate (≤7 visits) or high, (8 or more visits) and compared them with usual care participants. Improvements in composite measure (depressive symptoms and at least one of three cardio-metabolic) were the primary outcome.

Statistical Analysis: Mean levels of depression and cardio-metabolic measures were analysed over time using computer package IBM SPSS Statistics 25.

Results: The composite outcome was sustained the highest in the moderate engagers [27.5%, 95% confidence interval (CI): 19.5, 36.7] and the lowest in high engagers (15.8%, 95% CI: 8.1, 26.8). This pattern was observed for individual parameters - depressive symptoms and glycosylated haemoglobin. Progressive reductions in mean depressive symptom scores were observed for moderate engagers and usual care group from baseline to 36 months. However, in high engagers of collaborative care, mean depressive symptoms were higher at 36 months compared to 12 months.

Conclusion: Sustained benefits of collaborative care were larger in participants with moderate engagement compared with high engagement, although a majority of participants relapsed on one or more outcome measures by 36 months. High engagers of collaborative care for co-morbid depression and diabetes may need light touch interventions for longer periods to maintain health and reduce depressive symptoms.