Long-term clinical outcomes of care management for chronically depressed primary care patients: a report from the depression in primary care project.

PURPOSE: Recent studies examining depression disease management report improvements in short-term outcomes, but less is known about whether improvements are sustainable over time. This study evaluated the sustained clinical effectiveness of low-intensity depression disease management in chronically depressed patients.
METHODS: The Depression in Primary Care (DPC) intervention was introduced in 5 primary care practices in the University of Michigan Health System, with 5 matched practices selected as control sites. Clinicians were free to refer none, some, or all of their depressed patients at their discretion. Core clinical outcomes of remission and serial change in Patient Health Questionnaire (PHQ-8) scores for 728 DPC enrollees observed for up to 18 months after enrollment were compared with those for 78 patients receiving usual care who completed mailed questionnaires at baseline, 6, 12, and 18 months.
RESULTS: DPC enrollees had sustained improvement in remission rates and reduced-function days over the full 18 months. Mean change in the PHQ-8 score over each 6-month interval was more favorable for DPC enrollees than for usual care patients, and the proportion of DPC enrollees in remission was higher at 6 months (43.4% vs 33.3%; P = .11), 12 months (52.0% vs 33.9%; P = .012), and 18 months (49.2% vs 27.3%; P = .004). Multivariate analysis controlling for age, sex, ethnicity, baseline severity, and comorbid medical illness confirmed that DPC enrollees had significantly more reduction in depressive symptom burden over 18 months.
CONCLUSIONS: The DPC intervention produced sustained improvement in clinical outcomes over 18 months in a cohort of chronically depressed patients with persistent symptoms despite active treatment.