Background: Depression is common in older adults and often coexists with multiple chronic diseases, which may complicate its diagnosis and treatment.
Objective: To determine whether or not the presence of multiple comorbid medical illnesses affects patient response to a multidisciplinary depression treatment program.
Design, setting and participants: Preplanned analyses of Improving Mood-Promoting Access to Collaborative Treatment (IMPACT), a randomized controlled trial of 1801 depressed older adults (> or =60 years), which was performed at 18 primary care clinics from eight health care organizations in five states across the United States from July 1999 to August 2001.
Intervention: Intervention patients had access for up to 12 months to a depression care manager, supervised by a psychiatrist and a primary care expert, who offered education, care management and support of antidepressant management by the patient's primary care physician, or provided brief psychotherapy (Problem-Solving Treatment in Primary Care).
Measurements: Depression, quality of life (QOL; scale of 0-10) and mental health component score (MCS) of the Short-Form 12 assessed at baseline, 3, 6 and 12 months.
Results: Patients suffered from an average of 3.8 chronic medical conditions. Although patients with more chronic medical conditions had higher depression severity at baseline, the number of chronic diseases did not affect the likelihood of response to the IMPACT intervention when compared to care as usual. Intervention patients experienced significantly lower depression during all follow-up time points as compared with patients in usual care independent of other comorbid illnesses (P<.001). Intervention patients were also more likely to experience substantial response (at least a 50% reduction in depressive symptoms) regardless of the number of comorbidities, to experience improved MCS-12 scores at 3 and 12 months, and to experience improved QOL.
Conclusions: The presence of multiple comorbid medical illnesses did not affect patient response to a multidisciplinary depression treatment program. The IMPACT collaborative care model was equally effective for depressed older adults with or without comorbid medical illnesses.