Christine Bialonczyk

HIGH PLASMA LEVELS OF FACTOR VIII AND THE RISK OF RECURRENT VENOUS THROMBOEMBOLISM

BACKGROUND A high plasma level of factor VIII is a risk factor for venous thromboembolism. We evaluated the risk of a recurrence of thrombosis after an initial episode of spontaneous venous thromboembolism among patients with high plasma levels of factor VIII. METHODS We studied 360 patients for an average follow-up period of 30 months after a first episode of venous thromboembolism and discontinuation of oral anticoagulants. Patients who had recurrent or secondary venous thromboembolism, a congenital deficiency of an anticoagulant, the lupus anticoagulant, hyperhomocysteinemia, cancer, or a requirement for long-term treatment with antithrombotic drugs or who were pregnant were excluded. The end point was objectively documented, symptomatic recurrent venous thromboembolism. RESULTS Recurrent venous thromboembolism developed in 38 of the 360 patients (10.6 percent). Patients with recurrence had higher mean (+/-SD) plasma levels of factor VIII than those without recurrence (182+/-66 vs. 157+/-54 IU per deciliter, P=0.009). The relative risk of recurrent venous thrombosis was 1.08 (95 percent confidence interval, 1.04 to 1.12; P<0.001) for each increase of 10 IU per deciliter in the plasma level of factor VIII. Among patients with a factor VIII level above the 90th percentile of the values in the study population, the likelihood of recurrence at two years was 37 percent, as compared with a 5 percent likelihood among patients with lower levels (P<0.001). Among patients with plasma factor VIII levels above the 90th percentile, as compared with those with lower levels, the overall relative risk of recurrence was 6.7 (95 percent confidence interval, 3.0 to 14.8) after adjustment for age, sex, the presence or absence of factor V Leiden or the G20210A prothrombin mutation, and the duration of oral anticoagulation. CONCLUSIONS Patients with a high plasma level of factor VIII have an increased risk of recurrent venous thromboembolism.

Overweight, Obesity, and the Risk of Recurrent Venous Thromboembolism

BACKGROUND Excess body weight is a risk factor for a first venous thromboembolism. The impact of excess body weight on risk of recurrent venous thrombosis is uncertain. METHODS We studied 1107 patients for an average of 46 months after a first unprovoked venous thromboembolism and withdrawal of anticoagulant therapy. Excluded were pregnant patients, those requiring long-term antithrombotic treatment, and those who had a previous or secondary thrombosis, natural coagulation inhibitor deficiency, lupus anticoagulant, or cancer. Our study end point was symptomatic recurrent venous thromboembolism. RESULTS A total of 168 patients had recurrent venous thromboembolism. Mean (SD) body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) was significantly higher among patients with recurrence than among those without recurrence: 28.5 (6.0) vs 26.9 (5.0) (P = .01). The relationship between excess body weight and recurrence was linear; the adjusted hazard ratio for each 1-point increase in BMI was 1.044 (95% confidence interval [CI], 1.013-1.076) (P < .001). Four years after discontinuation of anticoagulant therapy, the probability of recurrence was 9.3% (95% CI, 6.0%-12.7%) among patients of normal weight and 16.7% (95% CI, 11.0%-22.3%) and 17.5% (95% CI, 13.0%-22.0%) among overweight and obese patients, respectively. Compared with patients of normal weight, the hazard ratio of recurrence adjusted for age, sex, factor V Leiden, prothrombin G20210A mutation, high factor VIII levels, and type of initial venous thromboembolic event was 1.3 (95% CI, 0.9-1.9) (P = .20) among overweight patients and 1.6 (95% CI, 1.1-2.4) (P = .02) among obese individuals. The population attributable risk corresponding to excess body weight was 26.8% (95% CI, 5.3%-48.2%). CONCLUSION Excess body weight is a risk factor of recurrent venous thromboembolism.

Basal high-sensitivity-C-reactive protein levels in patients with spontaneous venous thromboembolism

The role of C-reactive protein (CRP) in venous thromboembolism (VTE) is still under discussion because of controversial results in the literature. Conflicting data may have partly been due to bias by exogenous factors altering CRP levels. We investigated CRP concentrations in patients with spontaneous VTE applying a study design that allowed the measurement of basal high sensitivity (hs)-CRP levels. Patients with a history of deep vein thrombosis (DVT, n=117) and pulmonary embolism (PE, n=97) were compared to healthy individuals (n=104). Hs-CRP levels (mg/dl) were significantly higher in patients (n=214, median/interquartile range: 0.171/0.082-0.366) than in controls (0.099/0.053-0.245, p=0.001). The unadjusted odds ratio (OR) for VTE per 1 mg/dl increase of CRP was 2.8 [95% confidence interval (CI): 1.1-6.8, p=0.03]. This association remained significant after adjustment for factor V Leiden, prothrombin G20210A and factor VIII activity above 230% (OR = 2.9, 95% CI [1.1-7.5]), but became remarkably attenuated and lost its statistical significance after adjustment for BMI alone (OR = 1.7 [0.7-4.0]). CRP was also not independently associated with VTE in subgroups of patients (those with DVT without symptomatic PE, those with PE and patients without established risk factor) in multiple regression analysis. In summary, we observed significantly higher basal hs-CRP levels in patients with spontaneous VTE compared to healthy controls. This association was independent of hereditary and laboratory risk factors for VTE, but lost its significance after adjustment for BMI. Increased basal CRP levels do not appear to represent an independent risk factor for VTE.

Interleukin-6 and interleukin-6 promoter polymorphism (-174) G > C in patients with spontaneous venous thromboembolism.

Increased levels of interleukin-6 (IL-6) have been reported in patients with a history of venous thromboembolism (VTE); however, prospective studies did not confirm an association between inflammatory markers that are highly correlated with IL-6 and the risk ofVTE. It was the aim of our study to investigate the association of IL-6 and its promoter polymorphism (-174) G > C with the risk of spontaneousVTE. IL-6 was measured in 128 patients with deep venous thrombosis (DVT,70 w/58 m),105 with pulmonary embolism (PE, 58 w/47 m) and 122 healthy controls (60 w/62 m) with a highly sensitive ELISA (Quantikine HS Human IL-6 Immunoassay, RnDSystems). The promoter polymorphism was determined by genotyping, allele specific PCR was followed by high resolution gel-electrophoresis. Median concentrations [interquartile ranges] were 2.37 [1.51-3.89] (pg/ml) in patients with DVT, 2.83 [1.83-4.87] in those with PE and 2.51 [1.71-4.78] in controls (p = 0.6, p = 0.4). Hetero- or homozygous carriers of the C allele (71% in DVT, 67% in PE and 59% among controls) did not have higher IL-6 levels than homozygous carriers of the G allele (median 2.60 vs. 2.59 pg/ml, p = 0.7). In conclusion, we found no association of IL-6 and its promoter polymorphism (-174) G > C with the risk of spontaneous VTE.

Prediction of recurrent venous thromboembolism by measuring ProC Global.

In patients with venous thromboembolism (VTE) a laboratory assay that globally measures the overall thrombophilic tendency is not available. We hypothesized that determination of ProC((R)) Global, a plasma assay which tests the global function of the protein C pathway, could be used to stratify patients according to their risk of recurrent VTE. We prospectively followed 774 patients with first spontaneousVTE for a mean time of 52 months. ProC Global normalized ratio (NR) was measured in plasma by use of a commercially available assay based on activated partial thromboplastin time. Ninety-eight of the 774 patients had recurrentVTE. Patients with ProC Global NR > or = 0.75 had a relative risk of recurrence of 0.59 (95% CI 0.40-0.87) as compared with those with lower ratio. After four years, cumulative probability of recurrence was 8.6% in patients with ProC Global NR > or = 0.75 and 17.4% in patients with a lower ratio (p = 0.006). Patients with a high ProC Global NR have a low risk of recurrent VTE. ProC Global NR can be used to stratify patients with a first unprovoked VTE according to their risk of recurrence.

Is the determination of anti-beta2 glycoprotein I antibodies useful in patients with venous thromboembolism without the antiphospholipid syndrome?

Summary. Anti‐beta2‐glycoprotein I (beta2GPI) antibodies are frequently found in patients with lupus anticoagulant (LA). To investigate the prevalence of antibeta2GPI antibodies and their clinical impact in patients with a history of venous thromboembolism (VTE) without LA/anticardiolipin antibodies (ACA), we studied 503 patients [128 (36·2%) men, median age 41 years (interquartile range, IQR 28–54 years)] with previous thrombosis. A group of 113 individuals without VTE [43 (38·1%) men, age 46·7 years (IQR 38–52 years)] served as a control group. Among 418 patients without LA/ACA, anti‐beta2GPI‐IgG levels were elevated in seven (1·7%), ‐IgM in 15 (3·6%) and ‐IgA in 14 (3·3%) cases; in 58 patients with ACA, anti‐beta2GPI‐IgG levels were elevated in two (3·4%), six (10·3%) and three (5·2%), and in 27 with LA, they were elevated in 18 (66·7%), 19 (70·4%) and 10 (37%) respectively. Thus, the prevalence of elevated anti‐beta2GPI antibodies was not increased in patients without LA/ACA but was strongly associated with LA. Patients without ACA/LA who had a recurrent event did not have higher prevalence of elevated anti‐beta2GPI‐IgG, ‐IgM or ‐IgA antibodies than those without a recurrent event. Thus, elevated antibeta2GPI antibodies are not likely to be a predictor of recurrent events in patients without LA. We conclude that determination of anti‐beta2GPI antibodies does not improve the clinical management of patients with a history of VTE without LA/ACA.

The risk of recurrent venous thromboembolism in men and women

BACKGROUND Whether a patients sex is associated with the risk of recurrent venous thromboembolism is unknown. METHODS We studied 826 patients for an average of 36 months after a first episode of spontaneous venous thromboembolism and the withdrawal of oral anticoagulants. We excluded pregnant patients and patients with a deficiency of antithrombin, protein C, or protein S; the lupus anticoagulant; cancer; or a requirement for potentially long-term antithrombotic treatment. The end point was objective evidence of a recurrence of symptomatic venous thromboembolism. RESULTS Venous thromboembolism recurred in 74 of the 373 men, as compared with 28 of the 453 women (20 percent vs. 6 percent; relative risk of recurrence, 3.6; 95 percent confidence interval, 2.3 to 5.5; P<0.001). The risk remained unchanged after adjustment for age, the duration of anticoagulation, and the presence or absence of a first symptomatic pulmonary embolism, factor V Leiden, factor II G20210A, or an elevated level of factor VIII or IX. At five years, the likelihood of recurrence was 30.7 percent among men, as compared with 8.5 percent among women (P<0.001). The relative risk of recurrence was similar among women who had had their first thrombosis during oral-contraceptive use or hormone-replacement therapy and women in the same age group in whom the first event was idiopathic. CONCLUSIONS The risk of recurrent venous thromboembolism is higher among men than women.