Predictors of residual venous obstruction after deep vein thrombosis of the lower limbs: a prospective cohort study

Introduction: Delayed thrombus regression after deep vein thrombosis (DVT) of the lower limbs is associated with increased risk of DVT recurrence. Predictors of residual venous occlusion are unknown. We hypothesized that obesity, which causes reduced fibrinolytic activity, can predict delayed thrombus regression. Materials and methods: In a prospective cohort study, 98 patients with objective diagnosis of DVT underwent compression ultrasonography (CUS) after 6 and 12 months. Persistent occlusion was arbitrarily defined as a thrombus occupying, at maximal point of compressibility, more than 20% of the vein area in the absence of compression. The body mass index (BMI) and waist circumference were measured at baseline and at follow up to assess individual patterns of body fat distribution. Information on antithrombotic treatment, family history of varicose veins, cigarette smoking, concomitant disorders, the presence of known risk factors for DVT, the duration of anticoagulant treatment and the use of elastic stockings was collected. Results: Post-thrombotic recanalization was documented in 34 patients (34.7%) at 6 months and in 44 patients (44.9%) at 12 months. There was no difference in the mean BMI (p=0.469 at 12 months), in the prevalence of obesity (p=0.479) and visceral pattern of body fat distribution (p=0.239) between patients who did and did not show thrombus regression. The presence of a permanent risk factor for DVT was the only predictor of delayed thrombus regression (OR 11.0, 95% CI 1.359-61.978). Conclusions: Despite consistent evidence of impaired fibrinolysis, obesity is not associated with persistent venous obstruction.