Red cell distribution width (RDW) is a measure of the heterogeneity of cell size in the peripheral blood and has been shown to be an independent correlate of adverse outcomes in healthy participants and in some cardiac conditions. We examined the association between RDW and the complexity of coronary artery disease (CAD).
The study population included 193 nonanemic patients who had undergone coronary angiography for stable angina pectoris. Baseline RDW was measured as part of the automated complete blood count. Patients were classified depending on whether the SYNTAX score was 0 (no angiographically apparent CAD) or at least 1 where CAD was present angiographically.
Patients with angiographic CAD had significantly elevated RDW levels compared with the patients without CAD (14.4±1.3 vs. 12.5±0.9, P<0.001). There was a good correlation between RDW and the SYNTAX score (r=0.55, P<0.001). In a receiver operating characteristic curve analysis, an RDW value of 13.25 was identified as an effective cut-point in the segregation of the presence or absence of CAD [area under curve=0.87, 95% confidence interval (CI) 0.81–0.92]. An RDW value of more than 13.25 yielded a sensitivity of 84%, a specificity of 79%, a positive predictive value of 89%, and a negative predictive value of 71%. In multivariate analysis, RDW was observed to be an independent predictor for both angiographic CAD (odds ratio=4.80, 95% CI 2.41–9.57, P<0.001) and for a high (>32) SYNTAX score (odds ratio=2.28, 95% CI 1.45–3.60, P=0.01).
RDW is a readily available clinical laboratory value that is associated with both the presence and the complexity of CAD.