Red cell distribution width is associated with incident venous thromboembolism (VTE) and case-fatality after VTE in a general population

Recent studies suggest an association between red cell distribution width (RDW) and incident venous thromboembolism (VTE). We aimed to investigate the impact of RDW on risk of incident and recurrent VTE, and case-fatality, in a general population. RDW was measured in 26,223 participants enrolled in the Tromsø Study in 1994-1995. Incident and recurrent VTE events and deaths during follow-up were registered until January 1, 2012. Multivariate Cox proportional hazards regression models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI). There were 647 incident VTE events during a median of 16.8 years of follow-up. Individuals with RDW in the highest quartile (RDW≥13.3%) had 50% higher risk of an incident VTE than those in the lowest quartile (RDW≤12.3%). The association was strongest for unprovoked deep-vein thrombosis (HR highest vs lowest quartile of RDW: 1.8, 95% CI 1.1-3.1). VTE patients with baseline RDW≥13.3% had 30% higher risk of all-cause mortality after the initial VTE event than VTE patients with RDW<13.3%. There were no association between RDW and risk of recurrent VTE. Our findings suggest that high RDW is a risk factor of incident VTE, and that RDW is a predictor of all-cause mortality in VTE patients.