Depression and inflammation in patients with coronary heart disease: Findings from the heart and soul study

Background: Depression and inflammation independently predict adverse cardiovascular outcomes in patients with coronary heart disease (CHID). Depression has been associated with elevated levels of inflammation in otherwise healthy patients without known CHID. However, studies investigating the link between depression and inflammation in patients with established CHID have produced inconclusive results. Methods: We sought to examine the association of major depression with inflammation in 984 outpatients with established CHID from the Heart and Soul Study. We assessed current major depression with the Computerized Diagnostic Interview Schedule and collected venous blood samples for measurement of five inflammatory biomarkers (white blood cell count, CD40 ligand, C-reactive protein [CRP], fibrinogen, and interleukin-6 [IL-6]). We used multivariate analysis of variance to examine the association of current depression with inflammatory markers, adjusted for potential confounding variables. Results: Of the 984 participants, 217 (22%) had current major depression. Depression was not associated with increased levels of any inflammatory marker. Contrary to our hypothesis, depression was associated with lower levels of CRP (p = .09), fibrinogen (p = .006), and IL-6 (p = .007) in both unadjusted and adjusted models. Conclusions: We found no evidence that current depression is associated with greater inflammation in outpatients with CHID. Inflammation is unlikely to explain the adverse cardiovascular outcomes associated with depression in patients with established CHID.