Reduced calf muscle pump function is a risk factor for venous thromboembolism: A population-based cohort study

The calf muscle pump is a major determinate of venous return in the legs but has not been studied as a risk factor for venous thromboembolism (VTE). A population-based cohort study of Olmsted County, Minnesota residents was performed using calf pump function (CPF) measurements from venous plethysmography studies from 1998-2015. Patients with a history of VTE were excluded. Nursing validated VTE outcomes from the Rochester Epidemiology Project were identified after the index study date and patients with reduced CPF (rCPF) were compared to patients with normal CPF. 1532 patients with recorded CPF (28% air and 72% strain gauge plethysmography) were included: 591 (38.5%) had normal CPF, 353 (23.0%) had unilateral rCPF, and 588 (38.3%) had bilateral rCPF. Any VTE occurred in 87 patients (5.7%) after a median follow-up of 11.7 years (range 0-22.0 years; Table 2). Comparing patients with bilateral reduced to bilateral normal CPF, the unadjusted HR for incident VTE was 2.0 (95% CI 1.2-3.4) and after adjusting for age, BMI, and CCI, the HR was 1.68 (95% CI 0.98-2.89). The adjusted HR for ipsilateral DVT was evaluated in 3,064 legs comparing legs with reduced to normal CPF and was 1.71 (95% CI 1.03-2.84). Mortality was significantly higher in both the bilateral (p<0.001) and unilateral (p<0.001) rCPF groups compared to normal CPF. Our results demonstrate that CPF is a risk factor for VTE in an otherwise low-risk ambulatory population and might be a useful component in risk stratification models.