Depression and diabetes share a symbiotic relationship. While depression can stand in the way of effective diabetes management, diabetes and its complications can also make depression more intractable. Yet depression is twice as common in patients with diabetes compared with the general population, and its prevalence appears to increase with the number of diabetic complications. A new study now outlines a collaborative care approach that has been shown to be more effective than usual care in the management of depression in patients with more than 1 diabetic complication (J Gen Intern Med. 2006; 21:1036-1041).

The study included 329 patients with diabetes and comorbid depression who were recruited from 9 primary care clinics associated with a large health insurance plan. Participants were randomized to (1) a stepped-care depression treatment program headed by nurse depression care managers in collaboration with the primary care physician, or to (2) usual care, in which patients were advised to consult with their primary care physician about treatment (consisting, under that health plan, of antidepressant therapy) and were told they could self-refer to their health plan's mental health services.

Depression was assessed at baseline and at 3, 6, and 12 months using the Hopkins Symptom Checklist-20 (HSCL-20), a 20-item depression scale with a range of 0 to 4. Mean score at baseline was >1.1. A reduction in HSCL-20 score of ≥50% was considered a clinically significant improvement, and a score of <5 indicated remission.

Patients were stratified into 2 groups, based on the number of diabetes complications. At all time points, stepped care resulted in better depression outcomes than usual care among patients with multiple microvascular and macrovascular complications, even after controlling for appropriate variables. Improvements in depression scores persisted throughout the entire 12-month study period (Table).

In contrast, in the group that had no or only 1 complication, both types of depression treatment were equally and significantly effective.

A post hoc analysis revealed that patients who had at least 1 macrovascular complication derived the greatest benefits from the collaborative intervention for depression compared with usual care.

However, the authors note, "Although the intervention had beneficial effects on depressive symptoms in patients with 2 or more complications, a large proportion continued to have significant depressive symptoms at 12 months."

In addition, improvement in depression had no effect on hemoglobin A_1c, suggesting that an integrated intervention that addresses both depression and diabetes is needed.

ONLINE EXTRA
Stepped-care depression treatment algorithm.

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