Elsevier

Thrombosis Research

Volume 108, Issue 4, 25 November 2002, Pages 203-207
Thrombosis Research

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

https://doi.org/10.1016/S0049-3848(03)00063-XGet rights and content

Abstract

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.

Introduction

The presence of residual venous obstruction in patients with deep vein thrombosis (DVT) of the lower limbs was recently suggested as an independent risk factor for recurrent venous thromboembolism [1], [2]. Prandoni et al. [1] performed repeat compression ultrasonography (CUS) in 313 patients with proximal DVT and observed a full vein recanalization in 38.8% of patients after 6 months, in 58.1% after 1 year, in 69.3% after 2 years, and in 73.8% after 3 years. The presence of residual thrombosis was associated with a 2.9 hazard ratio to develop a recurrent event. Similarly, Piovella et al. [2] found that delayed thrombus regression predicted recurrent thrombosis with an odds ratio of 5.26 in a population of 283 patients with a previous first episode of DVT. In this study, cancer, younger age, and a DVT involving the entire femoro-popliteal axis resulted as independent negative predictors of CUS normalization. Yet, the mechanisms underlying delayed thrombus regression are still unclear. Indeed, impaired fibrinolytic activity may play a major role, and conditions associated with hypofibrinolysis in some patients might be associated with residual venous obstruction.

Our group [3] recently reported that the prevalence of overweight and obesity in a population of patients with previous DVT is higher than that of the general population, and that a significant weight gain occurs in the 6 months after the acute event. Obesity, in particular abdominal obesity, is a known risk factor for DVT and is an independent predictor for recurrent venous thromboembolism [4], [5], [6]. Impaired fibrinolytic activity has been consistently reported in obese patients [7], [8], [9], [10], and it was shown that increased levels of fibrinolytic inhibitors are proportionally related to increasing body mass index (BMI) [11]. The impaired fibrinolysis seems to be explained by production of type 1 plasminogen activator inhibitor (PAI-1) by the adipose tissue [12].

The aim of this prospective cohort study was to investigate whether increased BMI, patterns of body fat distribution, and weight changes following DVT are associated to delayed thrombus regression after 6 and 12 months.

Section snippets

Materials and methods

One hundred and ten consecutive patients with objective diagnosis of a first episode of symptomatic proximal DVT of the lower limbs were enrolled in the study. All patients had DVT diagnosed by compression ultrasound examination using a 3–11-MHz linear probe (Agilent Sonos 5500). The examination included the iliac, common and superficial femoral, and the popliteal veins. Patients were examined in the supine position and in the prone position with knees slightly flexed and feet supported by a

Results

Of the 110 consecutive patients initially enrolled in the study, three were subsequently lost to follow-up and nine had recurrent DVT and are thus excluded from this analysis. We therefore included 98 patients in our analysis. Baseline characteristics at the time of DVT diagnosis are summarized in Table 1. After 6 months, the number of obese patients increased, as we recorded a weight gain in 60 patients (61.2%) with a mean weight gain of 6.6% (±5.4%). Among the 76 patients who were overweight

Discussion

This prospective, cohort study failed to show any correlation between obesity and delayed thrombus regression. Obese patients, despite evidence of reduced fibrinolytic activity, had the same probability as lean patients to have persistent venous obstruction 12 months after their presenting DVT. The likelihood of CUS recanalization was not influenced by the BMI, by a visceral pattern of body fat distribution, or by significant weight gain. Among all other considered variables, only the presence

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