Table 4.

Studies exploring association between red blood cell distribution width (RDW) and coronary atherosclerosis.

First author, journal, year	Study design	Study population	Mean follow-up	Major outcomes	Major limitations
(i) Yalçin et al. [127] (ii) European Journal of General Medicine (iii) 2012	Cross-sectional and observational study	296 stable eligible patients, 71% (mean age 61 ± 11 years) of them had coronary artery disease and 29% (mean age 52 ± 11 years) of them had normal coronary arteries	—	Red blood cell distribution width values were significantly different among the subgroups determined for the severity and extent of coronary artery disease	(i) The sample size was relatively small (ii) It does not explain the exact mechanism (iii) Control group included the patients who are not completely normal (iv) Not rule out the possibility of residual confounding
(i) Çelik et al. [128] (ii) American Journal of Cardiology (iii) 2014	Retrospective analysis	572 patients without coronary artery disease history	—	(i) RDW was found to be higher in patients with critical stenosis, than those without (13.63 ± 1.28 versus 14.31 ± 1.58, p < 0.001) (ii) RDW was an independent predictor of the severity of atherosclerotic lesions	(i) No follow-up of the patient (ii) The sample size was relatively small
(i) Chaikriangkrai et al. [129] (ii) Arteriosclerosis, Thrombosis, and Vascular Biology Arteriosclerosis, Thrombosis, and Vascular Biology (iii) 2014	Cross-sectional study	832 patients without known coronary artery disease who presented with acute chest pain, age > 18 years	10	No association between RDW and coronary calcification presence or severity	(i) Causal relationship cannot be established from this study design (ii) Patients not having CBC performed were excluded, which might create a bias