Objective: A previous study described the effect of a collaborative care intervention on improving adherence to antidepressant medications and depressive and functional outcomes of patients with persistent depressive symptoms 8 weeks after the primary care physician initiated treatment. This paper examined the 28-month effect of this intervention on adherence, depressive symptoms, functioning, and health care costs.
Design: Randomized trial of stepped collaborative care intervention versus usual care.
Setting: HMO in Seattle, Wash.
Patients: Patients with major depression were stratified into severe and moderate depression groups prior to randomization.
Interventions: A multifaceted intervention targeting patient, physician, and process of care, using collaborative management by a psychiatrist and a primary care physician.
Measures and main results: The collaborative care intervention was associated with continued improvement in depressive symptoms at 28 months in patients in the moderate-severity group (F1,87 = 8.65; P =.004), but not in patients in the high-severity group (F1,51 = 0.02; P =.88) Improvements in the intervention group in antidepressant adherence were found to occur for the first 6 months (chi2(1) = 8.23; P <.01) and second 6-month period (chi2(1) = 5.98; P <.05) after randomization in the high-severity group and for 6 months after randomization in the moderate-severity group(chi2(1) = 6.10; P <.05). There were no significant differences in total ambulatory costs between intervention and control patients over the 28-month period (F1,180 = 0.77; P =.40).
Conclusions: A collaborative care intervention was associated with sustained improvement in depressive outcomes without additional health care costs in approximately two thirds of primary care patients with persistent depressive symptoms.