The predictive value of red cell distribution width in venous thromboembolism and related mortality

Background: Red cell distribution width (RDW) is a measure of red blood cell size variation and heterogeneity. Recent meta-analyses demonstrated this measurement could be strong predictor in coronary artery disease, chronic heart failure, and atrial fibrillation. Nevertheless, there is no meta-analysis evaluating the role of RDW in prediction of the occurrence of venous thromboembolism (VTE), the third most common cardiovascular disease, and related mortality. Objective: To investigate the association of RDW and VTE including deep vein thrombosis (DVT) and pulmonary embolism (PE) and related mortality. Methods: Major medical databases were systematically searched for observational studies which assessed the association of RDW and VTE published until May 2022. The databases were searched with predefined protocol without language restriction based on PRISMA guidelines. The analysis was performed in RevMan 5.3 to provide pooled measures for Risk Ratio (RR) and weighted mean difference (WMD). Results: Twenty-three studies were enrolled including 6,737 cases and 58,831 controls. Higher RDW was indicated as independent predictors for VTE compared to lower RDW (RR = 1.82, p < 0.00001), comprising DVT and PE (RR = 1.6, p < 0.00001, and RR = 2.05, p = 0.002, respectively). There was also an association between higher RDW and risk of mortality after PE episode with RR = 1.4 (p = 0.0004), involving short- (30-day) and long-term (> 1 year) mortality (RR = 1.79, p = 0.04, and RR = 1.15,p = 0.03, respectively). Compared to lower RDW, higher RDW also revealed a significant association with unprovoked VTE (RR = 2.18, p = 0.02). VTE-group had a higher mean of RDW compared to control with WMD = 1.13% (p < 0.00001), consisting of PE-group (WMD = 0.99%, p < 0.00001) and DVT-group (WMD = 1.07%, p < 0.00001). Among PE patients, The PE-related mortality group also had a higher mean of RDW in comparison to the survivor group with WMD = 1.97%, (p < 0.00001). Conclusions: Higher RDW value was associated with the occurrence of VTE, including DVT, PE, unprovoked VTE, and PE-related mortality. Therefore, the use of the potential role of RDW should be emphasized since it is low-cost and simple to obtain, even in a low-resource setting.