Mild depression versus C-reactive protein as a predictor of cardiovascular death: a three year follow-up of patients with stable coronary artery disease

Abstract

Objective:Depression is common in patients with coronary artery disease (CAD) and is associated with higher risk of cardiovascular adverse events. We aimed to explore the prognostic role of mild depression on cardiovascular mortality and compare its prognostic value with C-reactive protein (CRP) levels in patients with stable CAD.Research design and methods:We initially recruited 523 consecutive patients with stable CAD. Glucose, lipids and CRP levels were measured and an echocardiographic study was performed. In addition, depressive symptomatology was assessed with the Zung Depression Rating Scale (ZDRS, range 20–80). Patients on antidepressant treatment or with ZDRS score ≥60 were excluded. Patients were followed up at 6 month intervals (median 33 months, interquartile range 24–40 months) by telephone interview.Results:Follow-up data were obtained from 485 patients (92.7%). Nineteen patients with baseline CRP levels >10 mg/L and eight with non-cardiovascular death were excluded from analysis. Of the remaining 458 patients 113 (24.7%) presented cardiac events. Of them 21 died (4.6%), 42 developed acute coronary syndrome (9.2%), 27 (5.9%) had a revascularization procedure due clinical deterioration, two had a stroke (0.44%) and 21 (4.6%) an arrhythmic event. Multivariate Cox regression analysis showed that ZDRS score was independent predictor of cardiovascular death (hazard ratio [HR]: 1.104 with 95% confidence interval [CI]: 1.039–1.172, p = 0.001) after adjustment for conventional risk factors and CRP. The Wald test statistic of CRP was 2.59, whereas the Wald test statistic of ZDRS score was 3.23, indicating better predictability of ZDRS score. ZDRS score was also independent predictor of both cardiovascular death and arrhythmic event (HR: 1.102 with 95% CI: 1.051–1.156, p < 0.001) after adjustment for conventional risk factors and CRP levels. The main limitations of our study were the evaluation of depression at one point in time and the assessment of inflammatory burden by measuring only CRP levels.Conclusions:Mild depression is associated with increased cardiovascular mortality and is a better predictor than CRP levels in patients with stable CAD.