Increased level of red blood cell distribution width is associated with deep venous thrombosis.

Previous studies have demonstrated a significant association between red blood cell distribution width (RDW) and acute pulmonary embolism. To the authors' knowledge no study has been reported in patients with deep venous thrombosis (DVT). A total of 431 lower extremity venous duplex examinations were included in the study. Of these, 216 examinations with the diagnosis of DVT were compared to 215 examinations with normal duplex findings with respect to RDW. The two groups were well matched. DVT group had a higher median value and the interquartile range (25th and 75th) of RDW (%) level [14.9 (14.2-16.7)] compared to control group [14.4 (13.6-15.2); P < 0.001], respectively. Patients were divided into tertiles based on RDW. DVT was detected in 42 patients (31.6%) in the lowest tertile, in 81 (53.3%) in the middle tertile, and in 93 (63.7%) in the highest tertile (P < 0.001). In multivariate analysis after adjustment for confounding variables, RDW was the only parameter to predict the presence of DVT [odds ratio (OR) 1.37; 95% confidence interval (CI) 1.21-1.55; P < 0.001]. After removing patients with chronic DVT, the interquartile range (25th and 75th) of the RDW (%) level was also higher in the DVT group [15.0 (14.2-16.7)] compared with the control group [14.4 (13.6-15.2); P < 0.001], respectively. In addition, in proximal DVT, the significant difference continued to be present, although this significance was lost in distal DVT [14.4% (13.6-15.2) vs. 16.1% (15.1-17.4), P < 0.001 and 14.4% (13.6-15.2) vs. 14.3% (14.2-14.7), P = 0.959]. In multivariate analysis, RDW was an independent predictor of risk of proximal DVT (OR 1.60; 95% CI 1.39-1.84; P < 0.001). RDW (%) level was significantly higher in patients with bilateral DVT than in patients with unilateral DVT [16.0 (14.8-17.1) vs. 14.4 (14.2-14.8), P < 0.001, respectively]. In receiver operating characteristics curve analysis, RDW more than 14.9% had 85% sensitivity and 73% specificity in predicting proximal DVT. RDW, an inexpensive and easily measurable laboratory variable, was independently and significantly associated with the presence and severity of DVT, especially nonchronic proximal DVT. The mechanism of association requires, however, further study.