The risk of recurrent venous thromboembolism in heterozygous carriers of factor V Leiden and a first spontaneous venous thromboembolism

BACKGROUND: Factor V (FV) Leiden is a risk factor for venous thrombosis (VT). Data on its influence on the risk of recurrent venous thromboembolism (VTE) are controversial owing to different study designs and patient cohorts. METHODS: We reevaluated the risk of recurrence among heterozygous carriers and noncarriers of FV Leiden with a first spontaneous proximal VT of the leg and/or pulmonary embolism. Patients with secondary VTE, homozygous FV Leiden, natural inhibitor deficiencies, lupus anticoagulant, cancer, or long-term anticoagulation were excluded. The study end point was objectively documented, symptomatic, recurrent VTE. RESULTS: After discontinuation of oral anticoagulant therapy for a first VTE, we prospectively observed 287 patients, 83 (29%) of whom were heterozygous for FV Leiden. Recurrent VTE was seen in 17 (20%) of 83 patients with and 44 (21.6%) of 204 without FV Leiden. The probability of recurrence among heterozygotes was 12% (95% confidence interval [CI], 8%-16%), 27% (95% CI, 21%-33%), and 27% (95% CI, 21%-33%) after 2, 4, and 6 years, respectively, and was not higher than that among patients without the mutation (16%, 23%, and 34%, respectively). The relative risk of recurrence in heterozygotes was 0.9 (95% CI, 0.5-1.6; P =.60) after adjustment for confounding variables. The risk of recurrence among patients with and without FV Leiden was not different when sex distribution or duration of anticoagulation therapy was taken into account. CONCLUSIONS: The risk of recurrence is similar among carriers and noncarriers of FV Leiden. Heterozygous patients should receive secondary thromboprophylaxis for a similar length of time as patients without FV Leiden.     

The risk of pregnancy-related venous thromboembolism in women who are homozygous for factor V Leiden

The risk of venous thromboembolism (VTE) is increased in pregnancy and during the post-partum period. The absolute risk for pregnancy-related VTE in heterozygous women with the factor V Leiden mutation is approximately 2%, but studies on this risk for homozygous women show conflicting results. In a retrospective family study, we found that the risk of pregnancy-related VTE in women with a symptomatic first-degree relative was 17% per pregnancy (95%CI 4.7-37.4). Anticoagulant prophylaxis during the post-partum period appears to be indicated in asymptomatic homozygous women from symptomatic kindred, whereas this could be decided on an individual basis during pregnancy.     

Factor V HR2 haplotype: a risk factor for venous thromboembolism in individuals with absence of Factor V Leiden

Venous thromboembolism (VTE), including deep venous thrombosis (DVT) and pulmonary embolism (PE), occurs secondary to a number of hereditary and acquired disorders of hemostasis. A recently recognized polymorphism in Factor V (FV) gene H1299R (also named HR2) has been reported to be a possible risk factor for the development of VTE. The aim of this study is to evaluate the role of HR2 polymorphism in VTE in a group of Lebanese patients. Seventy-three VTE patients and 125 healthy subjects were examined for HR2. The average ages for the patients and controls were 45.0 ± 19.1 years and 35.4 ± 18.6 years, respectively. Sixty patients (82.2%) had DVT, eight patients (11%) had PE, and five patients (6.8%) had both. There was significant association between FV Leiden and VTE (p < 0.001). HR2 haplotype had a prevalence of 16.4% in patients. VTE patients with normal FV were 2.7 times more likely to have the HR2 haplotype as compared to controls with normal FV (p = 0.036, 95% CI = 1.04–7.06). We conclude that the FV HR2 haplotype significantly affects the risk of VTE in subjects with normal FV. This finding entails that screening for the HR2 haplotype should be done in VTE patients with normal FV Leiden results. No conflicts of interest. No source of funding.     

Factor V Leiden mutation and the risk of venous thromboembolism in pregnant women.

BACKGROUND AND OBJECTIVES: In this retrospective, single center, cohort study we assessed the risk of pregnancy-related venous thromboembolism (VTE) in women belonging to a large number of families identified because of a symptomatic proband with single identified factor V Leiden mutation. DESIGN AND METHODS: Female family members who had experienced at least one full-term pregnancy were enrolled in the study. Two hundred and seventy pregnancies occurred in 105 carriers and 215 pregnancies in 81 non-carriers of factor V Leiden mutation. RESULTS: The frequency of VTE was 6.4% for heterozygous, 16.7% for homozygous, 20% for double heterozygous carriers of thrombophilic defects, and 1.2% for non-carriers. The majority of VTE events related to pregnancy occurred in the post-partum period. The relative risks of developing pregnancy-related VTE in women who were carriers of heterozygous and homozygous (or combined heterozygous) factor V Leiden mutation as compared to non-carriers were 5.3 (95% CI, 0.6 to 43.9) and 15.4 (95% CI, 1.4 to 164), respectively. INTERPRETATION AND CONCLUSIONS: Factor V Leiden mutation is a risk factor for pregnancy-related VTE, especially in its homozygous form and in combination with other thrombophilic abnormalities. Screening of families with this mutation might be useful for women of fertile age, as they may take advantage from thromboprophylaxis during pregnancy and the post-partum period.     

Factor XIII Val34Leu and the risk of venous thromboembolism in factor V Leiden carriers

A mutation in factor XIII (Val34Leu) was reported to protect against venous thromboembolism. We evaluated the effect of Val34Leu on thrombotic risk in 352 factor V Leiden carriers who were first-degree relatives of 132 thrombotic propositi carrying factor V Leiden. The total observation period was 2,594 years in 92 Val34Leu carriers and 7,444 years in 260 non-carriers. The annual incidence of a first episode of venous thromboembolism was 0.31% in Val34Leu carriers and 0.44% in non-carriers [relative risk (RR) for venous thromboembolism: 0.7, 95% CI 0.3-1.5]. Age-specific RR for venous thromboembolism were (for Val34Leu carriers and non-carriers respectively): 1.0 (95% CI 0.3-3.2) in the age group of 15-30 years, 0.4 (95%, CI 0.05-3.0) in the age group of 30-45 years, 0.6 (95% CI 0.1-2.9) in the group aged 45-60 years and 0.5 (95% CI 0.06-4.5) in relatives older than 60 years. In conclusion, the impact of FXIII Val34Leu on the venous thromboembolic risk is modest, suggesting that screening for this mutation in factor V Leiden carriers is not justified.     

Activated protein C resistance and factor V Leiden mutation are independent risk factors for venous thromboembolism

BACKGROUND: Resistance to activated protein C due to the factor V R506Q (Leiden) mutation is the most common clotting abnormality in patients with venous thromboembolism. OBJECTIVE: To evaluate the risk for venous thromboembolism associated with the factor V Leiden mutation or with resistance to activated protein C in the general population. DESIGN: Cross-sectional survey. SETTING: General community of Vicenza, Italy. PATIENTS: A population-based sample of 15,109 white persons 18 to 65 years of age who were randomly selected from the census list. MEASUREMENTS: Sequential validated approach based on participants' reports and Doppler ultrasonography. Resistance to activated protein C was investigated in all participants; 2134 participants with resistance to activated protein C were screened for the factor V Leiden mutation. RESULTS: Carriers of the factor V Leiden mutation had a relative risk of 3.3 (95% CI, 1.7 to 6.1) for venous thromboembolism before 65 years of age. The fraction of cases attributable to the factor V Leiden mutation was 6.6%. By 65 years of age, 5.7% of carriers of the mutation had had venous thromboembolism, mostly after surgery. Participants with a reduced response to activated protein C were at higher risk even if they did not carry the mutation (odds ratio, 1.7 [CI, 1.0 to 2.7]); the attributable risk for venous thromboembolism was 5.1%. CONCLUSIONS: The factor V Leiden mutation and resistance to activated protein C are important, independent risk factors for venous thromboembolism. Screening strategies for the factor V Leiden mutation in patients undergoing surgery or experiencing major trauma cannot be recommended, but phenotypic evaluation of resistance to activated protein C should be encouraged in patients with venous thromboembolism.     

Obesity as a risk factor in venous thromboembolism

PURPOSE: Whether obesity is an independent risk factor for pulmonary embolism or deep venous thrombosis has not been fully determined. METHODS: We used the database of the National Hospital Discharge Survey to further investigate the potential risk of obesity in venous thromboembolic disease. RESULTS: The relative risk of deep venous thrombosis, comparing obese patients with non-obese patients, was 2.50 (95% confidence interval [CI] = 2.49-2.51). The relative risk of pulmonary embolism was 2.21 (95% CI = 2.20-2.23). Obese females had a greater relative risk for deep venous thrombosis than obese males, 2.75 (95% CI = 2.74-2.76) versus 2.02 (95% CI = 2.01-2.04). Obesity had the greatest impact on both men and women aged less than 40 years. CONCLUSION: The data indicate that obesity is a risk factor for venous thromboembolic disease in men as well as women.     

FV Leiden mutation and risk of recurrent venous thromboembolism in Serbian population

The absolute rate of recurrence of venous thromboembolism (VTE) is approximately 5% per year. There is a lower rate of recurrence in provoked VTE, and higher in idiopathic one. So far, there is no consensus whether hereditary thrombophilia should be considered as a persistent risk factor, and whether it requires long-term anticoagulant therapy. The aim of our study was to estimate the risk of recurrent VTE in patients carrying FV Leiden mutation in Serbian population.In retrospective study (1994-2006), we have evaluated the risk of recurrent VTE in 56 patients who are carriers of FV Leiden mutation, in comparison to group consisting of 56 patients non-carriers of FV Leiden mutation. Patients with FII G20210A and MTHFR C677T mutations, antiphospholipid antibodies, antithrombin III, protein C or protein S deficiency, malignancies and diabetes were excluded from the study.Recurrent VTE occurred in 44.6% of the patients, carriers of the FV Leiden mutations, vs. 26.7% in non-carriers group (P<0.05). The incidence rate was 3.7 and 2.2% per year, respectively. The estimated relative risk of recurrence for FV Leiden carriers was 1.67 (95% CI 0.99-2.81, P=0.049). The 60% of patients with mutation and only 13% without mutation develop rethrombosis during first year after discontinuance of therapy (P<0.01).In our study patients with symptomatic VTE who are carriers of the FV Leiden gene mutations have a higher risk of recurrent VTE than non-carriers. Our data suggest the importance of the FV Leiden mutation detection and the estimation of the clinical condition for successful secondary prophylaxis of VTE.     

Antiphospholipid antibodies as risk factor for venous thromboembolism

The aim of the following study was to determine the prevalence of lupus anticoagulant (LA) and anticardiolipin antibodies (ACL) in patients with a history of venous thromboembolism (VTE). The patient group comprised 218 subjects with VTE before the age of 45, recurrent VTE or thrombosis in an unusual site. The control group consisted of 218 age, and sex-matched healthy individuals. LA and/or ACL were detected in 19 among 218 patients (8.7%). Lupus anticoagulant was found in 17 patients with VTE and in none out of 218 controls. The odds ratio for having venous thromboembolism was 14.1 (95% CI: 1.8-108.8) for patients with LA. Lupus anticoagulant is significantly associated with VTE. The prevalence of anticardiolipin was similar in patients and in controls. The results of our study indicate that anticardiolipin antibodies are not associated with venous thromboembolism.     

Age as a risk factor for venous thromboembolism after major surgery

PURPOSE OF REVIEW: Postoperative deep venous thrombosis and pulmonary embolism are serious and potentially life-threatening complications that frequently occur after major surgery. Most guidelines for thromboprophylaxis use advancing age as a key component to estimate thromboembolic risk. The reported effect of age on postoperative venous thromboembolism varies widely, making it unclear whether age alone is a significant risk factor. This article reviews the recent literature on the effect of age on the incidence of postoperative venous thromboembolism. RECENT FINDINGS: Between 2003 and 2005, several cohort studies assessed the risk factors for postoperative venous thromboembolism, showing a variable effect of age on its incidence in the 2- to 3-month period after major surgery. Studies also revealed a significant difference in the effect of age on the incidence of venous thromboembolism depending on the type of surgery. Obesity, postoperative immobilization, the use of thromboprophylaxis, the nature of the surgery, and underlying comorbid conditions such as heart failure seem to have a greater influence on the risk of venous thromboembolism than does age. SUMMARY: The variation in the effect of age on postoperative venous thromboembolism likely depends on whether or not other comorbid conditions or age-related changes in functional status are considered as risk factors. When these other risk factors are taken into account, the effect of advanced age decreases. More research is needed to develop validated venous thromboembolism risk-prediction tools for specific types of surgery. By use of this information, the intensity and duration of postoperative thromboprophylaxis can be tailored to the level of risk, not just age alone.     

The prevalence of risk factors for venous thromboembolism among hospital patients.

BACKGROUND--This study provides an estimate of the prevalence of risk factors for venous thromboembolism among hospital patients. METHODS--The presence of risk factors for venous thromboembolism was determined from a retrospective review of the medical records of 1,000 randomly selected patients in 16 acute care hospitals in central Massachusetts. RESULTS--The most common risk factors for venous thromboembolism were age 40 years (59%) or more, obesity (28%), and major surgery (23%). The average number of risk factors increased with increasing age. One or more risk factors for venous thromboembolism were present in 78% of hospital patients, two or more in 48%, three or more in 19%, four or more in 6%, and five or more in 1%. CONCLUSION--Risk factors for venous thromboembolism are common among hospital patients, suggesting that prophylaxis should be widely employed. The cost-effectiveness and risk benefit of prophylaxis is well established in patients undergoing major surgery. Further studies are needed to confirm the benefit of prophylaxis in patients with nonsurgical risk factors for venous thromboembolism.     

Additional genetic risk factors for venous thromboembolismin carriers of the factor V Leiden mutation

Only a minority of subjects with factor V (FV) Leiden mutation develop venous thromboembolism (VTE), suggesting that additional genetic risk factors may be present in symptomatic carriers. We screened 157 unrelated carriers of the FV Leiden mutation with a first episode of VTE and 291 unrelated asymptomatic FV carriers for the presence of two frequent mutations, i.e. G20210A of the prothrombin gene and C677T of the methylenetetrahydrofolate reductase gene. Carriers with other inherited or acquired thrombophilia-associated abnormalities were excluded from analysis. Heterozygotes for the G20210A mutation were more prevalent among symptomatic carriers than in asymptomatic carriers (10.8% v 2.7%, P  < 0.0001); homozygotes for the C677T mutation were also more prevalent in symptomatic carriers (21.6% v 14.4%, P  = 0.05). Factor V Leiden carriers who had had a VTE episode during oral contraceptive intake were more frequently carriers of the G20210A mutation (14.3%, P  = 0.03). These results further support the idea that VTE in carriers of FV Leiden results from interaction with additional genetic or circumstantial risk factors, and that an accurate search for such factors is required to identify carriers at risk.     

Coincidence of 20210A prothrombin variant and factor V Leiden predisposing to venous thromboembolism

Coexistence of inherited and environmental risks leads to the high hazard of venous thromboembolism. In such cases, there might be difficulties in the diagnosis and treatment of recurrent episodes. The importance of Factor V Leiden and prothrombin variant 20210A in the pathogenesis of venous thromboembolic disease, is widely accepted, but the carriership of thrombophilic genes' variants is usually not sufficient for the development of the disease. We report two cases of familial thrombophilia with concurrent presence of prothrombin variant 20210A and factor V Leiden. In a 28-year-old woman: pregnancy, immobilization, obstetric intervention appeared to precipitate the thromboembolic complication. In the second patient, the genetic studies revealed both thrombophilic mutations which could predispose to the recurrent venous thromboembolism, previously thought to be idiopathic. We discuss diagnostic and therapeutic difficulties in such patients.