Although depression is a risk and prognostic factor for cardiovascular disease (CVD), depression trials involving cardiac patients have not observed the anticipated cardiovascular benefits. To test our hypothesis that depression treatment delivered before clinical CVD onset reduces risk of CVD events, we conducted an 8-year follow-up study of the Indiana sites of the Improving Mood-Promoting Access to Collaborative Treatment (IMPACT) randomized controlled trial.
Participants were 235 primary care patients 60 years or older with major depression or dysthymia who were randomized to a 12-month collaborative care program involving antidepressants and psychotherapy (85 without and 35 with baseline CVD) or usual care (83 without and 32 with baseline CVD). Hard CVD events (fatal/nonfatal) were identified using electronic medical record and Medicare/Medicaid data.
A total of 119 patients (51%) had a hard CVD event. As hypothesized, the treatment × baseline CVD interaction was significant (p = .021). IMPACT patients without baseline CVD had a 48% lower risk of an event than did usual care patients (28% versus 47%, hazard ratio = 0.52, 95% confidence interval = 0.31–0.86). The number needed to treat to prevent one event for 5 years was 6.1. The likelihood of an event did not differ between IMPACT and usual care patients with baseline CVD (86% versus 81%, hazard ratio = 1.19, 95% confidence interval, 0.70–2.03).
Collaborative depression care delivered before CVD onset halved the excess risk of hard CVD events among older, depressed patients. Our findings raise the possibility that the IMPACT intervention could be used as a CVD primary prevention strategy. Trial Registration: clinicaltrials.gov Identifier: NCT01561105.