Aging of the venous valves as a new risk factor for venous thrombosis in the elderly: the BATAVIA study

Unlabelled Box Essentials • Risk of venous thrombosis (VT) related to valve thickness and valvular reflux in unknown. • Venous valves and reflux were measured by ultrasonography in cases and controls aged 70+. • Risk of VT was associated with increased valve thickness and valvular reflux >1second. • Thickening of valves is a generic process: there was no difference between right and left legs. Summary: Background Increasing age is the strongest risk factor for venous thrombosis (VT). Increasing age has been related to a thickening of the venous valves and a decreased valvular function. The association between valve thickness and the risk of VT is not known. Objectives To assess the association between increased valve thickness and valve closure time (VCT) and the risk of VT. Methods Analyses were performed in the BATAVIA study, including 70 cases aged 70 + with a first VT and 96 controls. We performed an ultrasound examination of the valves in the popliteal veins. The valves were imaged with a 9 MHz linear probe using B‐mode ultrasonography. VCT was measured as an indicator for valve function using an automatic inflatable cuff. To estimate the risk of VT, valve thickness was dichotomized at the 90th percentile as measured in controls and VCT was dichotomized at 1 s. Results Mean valve thickness of controls was similar in the left (0.36 mm, 95% CI 0.34–0.37) and right (0.36 mm, 95% CI 0.35–0.38) leg. In 45 cases a valve was observed in the contralateral leg with a mean valve thickness of 0.39 mm (95% CI 0.36–0.42). Cases had an increased valve thickness compared with controls: mean difference 0.028 mm (95%CI 0.001–0.055). Valve thickness > 90th percentile increased the risk of VT 2.9‐fold. Mean VCT in controls was 0.38 s, in contralateral leg of cases 0.58 s. VCT > 1 s increased the risk of VT 2.8‐fold (95% CI 0.8–10.4). Conclusions Risk of VT was associated with increased valve thickness and valvular reflux of > 1 s.