Abstract

Abstract 101

Objective:

To date, only a few case studies have reported occurrence of thrombosis in patients with VonWillebrand disease (VWD). No studies have looked at its incidence in this patient population. The aim of this study was to test our hypothesis that decreased VonWillebrand factor (VWF) levels confer a protective effect on arterial and venous thrombosis.

Methods:

This is a retrospective cohort study including patients (n = 350) with the ICD-9 code of VonWillebrand disease who were identified from our hospital database over a period of 25 years (Jan 1985 – Dec 2010). An extensive review of the patients' medical records was carried out to authenticate VonWillebrand disease, after which 198 patients were included in the analysis. A random parallel control sample without VonWillebrand disease matched for age, sex, hypertension, hyperlipidemia, atrial fibrillation and diabetes mellitus was also obtained from the hospital database. The primary outcomes were incidence of diagnosis of symptomatic arterial thrombosis [Cardiovascular events (CAD): Unstable angina, Q wave and non Q wave Myocardial infarction; Cerebrovascular events (CVD): stroke and transient ischemic attack] and venous thrombosis [deep vein (DVT), cerebral vein, portal vein, renal vein thrombosis and pulmonary embolism (PE)]. The results were computed using multivariate conditional logistic regression analysis and proportions were compared using McNemer'sChi – square test.

Results:

Out of 198 patients (mean age 44.2 ± 17.5, women 72%) with VWD, the incidence of arterial and venous thrombosis is reported in table 1.VWD was found to be an independent protective predictor from arterial thrombosis (OR 0.28, 95% CI 0.14 – 0.54, p <0.0001), more so in CAD (OR 0.28, 95% CI 0.12 – 0.64, p = 0.002) than in CVD (OR 0.28, 95% CI 0.10 – 0.77, p = 0.01). However this was not the case in venous thrombosis as seen in DVT (OR 0.62, 95% CI 0.20 – 1.93, p = 0.41) or PE (OR 0.50, 95% CI 0.09 – 2.75, p = 0.423).One case of portal vein thrombosis was also seen. Also the arterial thrombosis in VWD was not a predictor of mortality; 10 deaths were reported in VWD patients, while 4 in control population (OR 1.8, 95% CI 0.49 – 6.76, p = 0.37).

Conclusion:

In a population of relatively younger individuals with VonWillebrand disease, our study suggests a reduced incidence of arterial thrombosis but not in venous thrombosis. This brings up the possibility that there are could be other pathways or factors involved in arterial and venous thrombosis. To our knowledge, this is the first large observational study that has provided insight into the thrombotic disease in this group of patients.

Table 1:

Incidence rate of thrombosis.

Type of ThrombosisCases (%)Controls (%)p-value
CAD 8/198 (4%) 26/198 (13%) 0.001 
CVD 5/198 (2.5%) 17/198 (8.5%) 0.009 
DVT 5/198 (2.5%) 8/198 (4%) 0.41 
PE 2/198 (1%) 4/198 (2%) 0.42 
Type of ThrombosisCases (%)Controls (%)p-value
CAD 8/198 (4%) 26/198 (13%) 0.001 
CVD 5/198 (2.5%) 17/198 (8.5%) 0.009 
DVT 5/198 (2.5%) 8/198 (4%) 0.41 
PE 2/198 (1%) 4/198 (2%) 0.42 

Abbreviations; CAD, Coronary Artery Disease; CVD, Cerebrovascular Disease; DVT, Deep venous thrombosis; PE, Pulmonary Embolism

Disclosures:

No relevant conflicts of interest to declare.

Author notes

*

Asterisk with author names denotes non-ASH members.