Donate Help Contact The AHA Sign In Home
American Heart Association
Arteriosclerosis, Thrombosis, and Vascular Biology
Search: search_blue_button Advanced Search
« Previous Article | Table of Contents | Next Article »
Arteriosclerosis, Thrombosis, and Vascular Biology. 2001;21:731-738

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kamphuisen, P. W.
Right arrow Articles by Bertina, R. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kamphuisen, P. W.
Right arrow Articles by Bertina, R. M.
Related Collections
Right arrow Arterial thrombosis
Right arrow Deep vein thrombosis
Right arrow Coagulation
Right arrow Thrombophilia
Right arrow Thrombosis risk factors
(Arteriosclerosis, Thrombosis, and Vascular Biology. 2001;21:731.)
© 2001 American Heart Association, Inc.

Brief Review

Elevated Factor VIII Levels and the Risk of Thrombosis

Pieter W. Kamphuisen; Jeroen C. J. Eikenboom; Rogier M. Bertina

From the Hemostasis and Thrombosis Research Center, Department of Hematology, Leiden University Medical Center, Leiden, the Netherlands.

Correspondence to Rogier M. Bertina, Hemostasis and Thrombosis Research Center, Leiden University Medical Center, C2-R, PO Box 9600, 2300 RC Leiden, Netherlands. E-mail R.M.Bertina{at}lumc.nl


Key Words: thrombosis • factor VIII • von Willebrand factor • blood group


*    Introduction
up arrowTop
 *Introduction
down arrowDeterminants of Plasma Factor...
 down arrowElevated Factor VIII Levels...
 down arrowShould We Screen Patients...
 down arrowConclusions
 down arrowReferences
 
In vivo, a delicate balance exists between fibrin formation and fibrinolysis. Reduced blood flow, changes in the vessel wall, and changes in blood composition (hypercoagulability)1 may all result in a disturbance of this balance, which favors fibrin formation and ultimately may lead to the formation of occlusive thrombi. Venous thromboembolism is the result of clot formation in a vein at sites of reduced blood flow. Arterial thrombosis involves the formation of platelet aggregates at high shear rates at sites of vessel-wall injury.

Classic acquired risk factors for venous thrombosis include trauma, immobilization, pregnancy, surgery, malignancy, and infection. These are all factors that may cause tissue damage, stasis of the blood, or changes in blood composition. Inherited risk factors for venous thrombosis,2 3 4 5 most of which concern defects in the procoagulant and anticoagulant pathways, account for a substantial proportion of all thrombotic events. Table 1Down summarizes prevalences and relative risks of established genetic risk factors.6 7 8 9


View this table:
[in this window]
[in a new window]
  		Table 1. Genetic Risk Factors for Venous Thrombosis: Prevalence and Relative Risk

These risk factors include factor V Leiden (resistance to activated protein C [APC]),9 prothrombin 20210A,8 and deficiencies in antithrombin,2 protein C,3 4 and protein S.5 10 11 Elevated fibrinogen,12 antiphospholipid antibodies,13 and mild hyperhomocysteinemia14 are examples of laboratory phenotypes associated with venous thrombosis. Some of these phenotypes have also been found to be associated with arterial thrombosis.15 16 17 Whether this is also true for genetic risk factors such as factor V Leiden or the prothrombin 20210A allele is still uncertain.18 19 20 21 22 23 24 25 26

Despite growing insight in the pathogenesis of thrombophilia, the cause of many thrombotic episodes remains unknown. Recently, new laboratory phenotypes that are associated with an increased risk of venous thrombosis have been reported .27 28 29 One of these is an elevated factor VIII level. High factor VIII levels are a common risk factor for venous thrombosis27 30 31 and may also be associated with the risk of arterial thrombosis in coronary heart disease32 33 and stroke.34

The regulation of plasma factor VIII levels is complex. Most factor VIII circulates as a complex with von Willebrand factor (vWF),35 36 the levels of which are known to be dependent on factors such as blood group37 38 39 and endothelial stimulation.40 41 This highly complicates the study of the molecular basis of elevated factor VIII levels.

In the present review, we will summarize the present knowledge on the relation between factor VIII and thrombosis and discuss the possible determinants of elevated factor VIII levels in plasma.


*    Determinants of Plasma Factor VIII Levels
up arrowTop
 up arrowIntroduction
 *Determinants of Plasma Factor...
down arrowElevated Factor VIII Levels...
 down arrowShould We Screen Patients...
 down arrowConclusions
 down arrowReferences
 
Genetic Determinants of Plasma Factor VIII Levels
In healthy individuals, family studies have indicated a genetic influence on the level of factor VIII:C.42 43 Factor VIII levels varied less among twins than among unrelated individuals. Filippi et al44 have suggested a primary role of X-linked genetic determinants on the basis of the observation of a positive correlation of factor VIII:C levels within groups of male pairs who had identical X alleles. Ørstavik et al39 found that the variance of factor VIII and vWF:Ag levels was smaller within twin pairs than between these pairs. They estimated that 57% of the total variation in plasma factor VIII levels and 66% of the variation in vWF levels were genetically determined. Most recently, Souto et al45 reported a heritability of 0.4 for factor VIII levels in the families of the Genetic Analysis of Idiopathic Thrombosis (GAIT) study.

vWF and blood group are important determinants of the factor VIII level in plasma. The blood group non-O is associated with higher vWF and factor VIII levels than is blood group O,37 38 39 with a mean difference of 31.5 IU/dL for vWF:Ag and 22.4 IU/dL for factor VIII:C.46 Individuals with blood group AB have the highest vWF levels, whereas AA, AO, BB, and BO genotypes have intermediate levels.37 47 48 Most of the effect of blood group on the factor VIII level is mediated through vWF.38 46 Blood group A, B, and H(O) oligosaccharide structures have been identified on vWF,49 50 which may affect the clearance of vWF and, thus, of the vWF/factor VIII complex.51 52 Indeed, in patients with hemophilia A, the half-life of infused factor VIII was shorter in patients with blood group O (15.3 hours) than in patients with blood group A (19.7 hours).53 Both are much longer than the half-life of uncomplexed factor VIII as determined in patients with severe von Willebrand disease (2.8 hours).54 Interestingly, ABO blood group and plasma vWF level are independent predictors of factor VIII half-life.53

The high levels of factor VIII in patients with thrombosis persist over time31 55 and are, in general, not caused by acute-phase reactions.30 31 56 In addition, O’Donnell et al55 showed that only 50% of these persistently high factor VIII levels were associated with high vWF:Ag levels, indicating that vWF is not always responsible for high factor VIII plasma levels.

Factor VIII:C levels show a familial clustering, which remains after adjustment for the influence of vWF and blood group.46 Analysis of familial aggregation of factor VIII levels >=150 IU/dL in 12 large thrombophilic families57 identified blood group as the main determinant: 86% of the subjects with factor VIII levels >=150 IU/dL had blood group non-O. However, after adjustment for blood group and age, factor VIII levels >=150 IU/dL still aggregated in these families. Others have also observed a high concordance of factor VIII levels between first-degree relatives of patients with thrombosis with high factor VIII levels.31 58

So far, no variations in the factor VIII or vWF gene that are associated with high factor VIII levels have been identified. No sequence variations were found in the promoter and 3' terminus of the factor VIII gene in 62 patients with thrombosis with high factor VIII levels.59 Furthermore, we found no clear association between vWF or factor VIII:Ag levels and polymorphisms in the promoter (-1793 C/G, -1234 C/T, -1185 A/G, and -1051 G/A) and factor VIII binding region (2615 A/G and 2805 G/A) of the vWF gene.60 However, Keightley et al61 reported a significant association between vWF levels and the -1234 C/-1185A/-1051G allele in group O blood donors aged >40 years. No association was found between 2 highly informative CA repeats in the factor VIII gene (intron 13 and 22) and plasma levels of factor VIII:Ag.60 Therefore, other genes may be implicated in the regulation of plasma vWF and factor VIII levels. Finally, factor VIII levels are influenced by sex (higher in women than men) and race (higher in blacks than whites).61 62

Other Determinants of Plasma Factor VIII Levels
Body mass index (positively correlated with factor VIII levels) and higher levels of glucose (diabetes mellitus), insulin, fibrinogen, and triglycerides are also associated with increased factor VIII levels.33 63 64 Factor VIII levels increase with age, with an average rise of 5 to 6 IU/dL per decade.46 63 Oral contraceptives seem to have no effect on factor VIII levels.63 65

Several stimuli can cause a transient or sustained increase in factor VIII levels. Exercise transiently induces a rise of factor VIII that is probably a result of adrenalin and ß2-adrenoreceptor stimulation.66 67 68 69 70 71 Also, 8-arginine vasopressin and its analogue 1-deamino-8-D-arginine vasopressin enhance plasma vWF and factor VIII levels indirectly or directly via signaling via the V2 receptor.72 Sustained rises in factor VIII are seen during pregnancy, surgery, chronic inflammation, malignancy, liver disease, hyperthyroidism, intravascular hemolysis, and renal disease.73 74 In most conditions, there is a concordant increase of factor VIII and vWF:Ag levels.

Determinants of High Factor VIII Levels
Apart from the ABO blood group, no genetic components have been identified that are associated with high plasma factor VIII levels.

Possible determinants of elevated factor VIII levels are summarized in Table 2Down. The main determinant is an elevated vWF level, which is under the control of autosomal genes. The ABO blood group, which is the best-characterized modifier of the plasma vWF level, explains {approx}30% of the genetically determined variation in vWF levels.39 In humans, the majority of genetic factors regulating vWF remain to be determined. Candidate genes include a variety of genes coding for proteins involved in the biosynthesis and clearance of vWF.75 In mice, 2 modifier loci of vWF have been identified, 1 of which concerns an N-acetylgalactosaminyltransferase gene.76 77 Other important determinants of vWF level are age, acute phase, stress, and endothelial dysfunction.


View this table:
[in this window]
[in a new window]
  		Table 2. Possible Determinants of High Factor VIII Levels

Twenty-six percent of the subjects with factor VIII:Ag levels >=150 IU/dL have vWF levels <150 IU/dL,60 and only 50% of patients with thrombosis with sustained factor VIII:C levels >=150 IU/dL also have persistent high vWF:Ag levels.55 This illustrates that there are determinants of elevated factor VIII levels that do not act via vWF. Differences in genetically defined binding affinities of vWF and factor VIII may result in variations of plasma factor VIII levels that are not explained by variations in the vWF level. Differences in the stability of unbound factor VIII, which normally has a very short half-life, may also play a role.54

Factors V and VIII are related proteins and share common biosynthetic pathways, as reflected by recent studies of Nichols and colleagues78 79 and Neerman-Arbez et al80 in combined factor V and VIII deficiencies. The gene coding for the ER-Golgli Intermediate Compartment protein ERGIC-53 was shown to have quantitative effects on factor VIII levels. Factor V:Ag levels are correlated to some extent with plasma factor VIII:Ag levels,81 suggesting that common posttranslational modifications may explain part of the large variation in plasma factor V and VIII levels.

In all studies investigating the effect of high factor VIII on thrombosis, subjects with malignancy or chronic diseases were excluded, which makes the contribution of inflammation to high factor VIII levels in these groups small. Most likely, high factor VIII levels are the result of a combination of genetic and acquired factors.


*    Elevated Factor VIII Levels and Thrombosis
up arrowTop
 up arrowIntroduction
 up arrowDeterminants of Plasma Factor...
 *Elevated Factor VIII Levels...
down arrowShould We Screen Patients...
 down arrowConclusions
 down arrowReferences
 
Arterial Thrombosis
Low Factor VIII Levels
In 1989, a study by Rosendaal et al82 reported that low factor VIII levels protect against ischemic heart disease. Mortality due to ischemic heart disease is much lower in patients with hemophilia A than in the general male population,82 83 which may suggest that factor VIII is involved in the pathogenesis of arterial thrombosis. Also vWF, the main determinant of the factor VIII level in plasma, may play a role in the pathogenesis of atherothrombosis. Autopsy findings from patients with severe von Willebrand disease have shown extensive atherosclerosis but no occlusive arterial thrombi,84 85 which suggests that even very low vWF levels may not fully protect against the development of atherosclerotic lesions. Similarly, dogs with severe von Willebrand disease and undetectable vWF levels did not develop acute occlusive thrombi in atherosclerotic arteries,86 suggesting that vWF supports the progression of microthrombi into occlusive thrombosis.

High Factor VIII Levels
The first reports on a possible association between factor VIII and coronary artery disease date from the early 1960s.87 In the same period, blood group non-O and high factor VIII–related antigen (vWF) were identified as candidate risk factors for atherothrombotic disease.88 89 90 91 Later, the clarification of the mutual relationships between blood group, vWF, and factor VIII allowed a better appreciation of these early findings. Since then, several case-control studies have reported the association of factor VIII with coronary heart disease.91A

Several (but not all) large prospective studies in healthy individuals report an association between elevated factor VIII:C and vWF levels and the incidence of ischemic heart disease, especially fatal events (Table 3Down). After correction for other cardiovascular risk factors, this association was eliminated in the Atherosclerosis Risk in Communities (ARIC) Study33 but not in the Caerphilly Heart Study,94 leaving the possibility open that factor VIII:C and vWF have an effect on cardiovascular risk. More recently, the prospective Cardiovascular Health Study showed that elevated factor VIII levels were associated with cardiovascular disease and mortality in elderly men also.92 vWF levels were also predictive for cardiovascular events in patients with stable angina pectoris.93


View this table:
[in this window]
[in a new window]
  		Table 3. Prospective Studies on Relationship Between Factor VIII and vWF Levels and Risk of Coronary Heart Disease

Regarding the risk of stroke, the ARIC Study showed that per SD increase in factor VIII and in vWF, the risk increased 1.34-fold (95% CI 1.2 to 1.5) and 1.36-fold (95% CI 1.2 to 1.5), respectively.34 In addition, elevated vWF levels were associated with mortality in patients who had previously suffered from stroke.95

From these data and many similar data in the literature, it can be concluded that vWF and factor VIII levels are associated with a moderate increased risk of arterial thrombosis with similar risk estimates for both factors. In the Caerphilly Heart Study,95 8.9% of the patients with ischemic heart disease had factor VIII levels exceeding 123 IU/dL, with an associated relative risk of 1.9. This results in a population-attributable risk of 4%; ie, 4% of all arterial thrombotic events would have been prevented if this risk factor was eliminated, provided that the relation between factor VIII and arterial thrombosis is causal.96

Potential Mechanisms for the Relation of High Factor VIII Levels to Arterial Thrombosis
Several studies have addressed whether vWF or factor VIII is the causative factor in arterial thrombogenesis and whether the risk of high vWF and factor VIII is blood group dependent. Meade et al32 found that factor VIII remained associated with ischemic heart disease after adjustment for blood group, without taking vWF into account. Also in the Hoorn study (Jager et al97 ), high vWF levels were associated with cardiovascular mortality independent of blood group in diabetic and nondiabetic subjects. When vWF and factor VIII are mutually adjusted for, neither of the 2 remained associated with coronary disease.95 Therefore, it is likely that factor VIII and vWF increase the risk of arterial thrombosis, independent of blood group.

The ARIC Study demonstrated strong associations of factor VIII and vWF with risk factors for atherosclerosis,63 such as hypertension, diabetes, body mass index, and triglycerides. Some of these factors are known to be associated with perturbed endothelial and vascular inflammation.98 99 High shear forces, such as those that occur in stenosed vessels, increase vWF secretion by vascular endothelium41 and, thus, will stimulate platelet adhesion and aggregation at the site of damaged arterial walls, which may lead to thrombus formation.100 This may explain why elevated factor VIII and vWF levels are associated with stroke in subjects with presumed large-vessel disease,97 which is mainly the result of atherothromboembolism.101 At the same time, high factor VIII levels may stimulate the formation of thrombin and, thus, result in increased platelet activation and fibrin formation, processes that may contribute to the development of large occlusive thrombi from the microthrombi initially formed on the damaged endothelium.

Is there a causal relationship between high factor VIII and vWF levels and arterial thrombosis? Atherosclerosis itself could have affected the clotting factor levels by chronic inflammatory responses and elevated factor VIII, or vWF levels may reflect the inflammation and progression of atherosclerosis.93 However, such a model cannot explain the association between blood group (which is genetically determined) and cardiovascular disease,32 102 103 unless blood group does not act via vWF. Furthermore, the effect of factor VIII and vWF on arterial thrombosis was not attenuated after adjustment for age and other classical risk factors, such as hypertension, body mass index, cholesterol, and baseline ischemic heart disease.95 Even C-reactive protein, a strong marker of inflammation, did not clearly affect the risk associated with high vWF levels.97 The lack of association between factor VIII and vWF levels with carotid intima-media thickness among subjects with prevalent cardiovascular disease is another argument against elevated factor VIII/vWF being simply the consequence of atherosclerosis.104 In conclusion, it seems likely that high factor VIII and vWF levels have independent roles in increasing the risk of arterial thrombosis. The latter hypothesis is supported by the low cardiovascular mortality in patients with hemophilia A.82

Venous Thrombosis
High Factor VIII Levels
In 1969, Jick et al105 reported that blood group non-O is associated with an increased risk of venous thrombosis. Today, we know that individuals with blood group non-O have higher levels of vWF and factor VIII than do those with blood group O.37 38 39 91 106 In a large population-based case-control study on venous thrombosis (the Leiden Thrombophilia Study), blood group non-O, vWF:Ag, and factor VIII:C levels were all associated with an increased risk for venous thrombosis by univariate analysis.27 In multivariate analysis, factor VIII:C levels remained a risk factor for thrombosis, but the effect of blood group and vWF:Ag on thrombosis largely disappeared. This suggests that factor VIII is an independent risk factor for venous thrombosis and that vWF and blood group are only risk factors insofar as they affect the factor VIII level.27 Table 4Down shows the risk of thrombosis for approximate quartiles of factor VIII:C. There is a clear dose-dependent relation between factor VIII levels and risk of thrombosis. The adjusted relative risk for factor VIII:C levels >=150 IU/dL compared with levels <100 IU/dL is 4.8 (95% CI 2.3 to 10.0). Compared with subjects with levels <150 IU/dL, subjects with levels >=150 IU/dL have a 3-fold increased risk. Furthermore, each increase in the factor VIII:C level of 10 IU/dL is associated with a 10% increase in the risk of a first thrombotic event.31 56


View this table:
[in this window]
[in a new window]
  		Table 4. Relative Risk of Thrombosis for Categories of Factor VIII:C Levels

The association between high factor VIII:C levels and venous thrombosis has been confirmed in several independent studies.30 31 107 Also, high factor VIII antigen (factor VIII:Ag) levels are associated with venous thrombosis in the Leiden Thrombophilia Study. The relative risk for venous thrombosis of factor VIII:Ag levels >=150 IU/dL is 5.3 (95% CI 2.7 to 10.1) compared with levels <100 IU/dL,108 which is very similar to the risk previously reported for factor VIII activity levels >=150 IU/dL.27 After excluding all subjects with factor V Leiden, prothrombin 20210A mutation, and a deficiency of protein C, protein S, or antithrombin (defined as previously described6 ) or of lupus anticoagulant, the thrombosis risk for factor VIII:Ag levels >=150 IU/dL is still increased (odds ratio 4.7, 95% CI 2.3 to 9.3).

The prevalence of elevated factor VIII levels is high: 25% of patients with a first episode of deep-vein thrombosis and 11% of healthy control subjects have factor VIII levels >=150 IU/dL.27 The estimated population-attributable risk for factor VIII levels >=150 IU/dL is {approx}16%. With a causal relationship between high factor VIII and venous thrombosis presumed, 16% of all deep-vein thromboses in the population are the result of high factor VIII levels, indicating that this is an important prothrombotic risk factor.

There are several studies reporting that high levels of factor VIII are associated with an increased risk of recurrences of thrombosis. Kraaijenhagen et al31 found factor VIII levels >=150 IU/dL in 57% of patients with recurrent venous thrombosis. Kyrle et al109 followed 360 patients with venous thromboembolism and found a recurrence in 27% of patients with factor VIII levels >234% (90th percentile in the patient group!) and in 9% of patients without elevated factor VIII levels.

Interaction of Factor VIII and Other Risk Factors for Thrombosis
In thrombophilic families in which protein C deficiency and factor V Leiden were both present, a history of thrombosis was present in 31% of individuals with protein C deficiency, in 13% of individuals with factor V Leiden, and in 73% of subjects with the combined defects.110 In addition, selected patients from thrombophilic families with factor V Leiden have, on average, a lower median age at the first thrombotic event (29 years) than "unselected" consecutive thrombotic patients with factor V Leiden (43 years).111 These observations suggested that venous thromboembolism is a multicausal disease and that several risk factors for thrombosis need to accumulate in the individual before a threshold is passed and a thrombotic event will occur.112

Recently, the influence of high factor VIII levels on the occurrence of venous thrombosis was investigated among the relatives of symptomatic factor V Leiden carriers.113 Compared with their relatives with either high factor VIII or factor V Leiden, first-degree relatives with the combination of a factor VIII level >=150 IU/dL and factor V Leiden had an increased rate of venous thrombosis. This means that factor VIII levels >=150 IU/dL will contribute to the risk of venous thrombosis of factor V Leiden carriers.

Factor VIII levels >150 IU/dL also affected the thrombotic risk of oral contraceptive users. In women with factor VIII:C >=150 IU/dL, the risk associated with oral contraceptive use was 10.3 (95% Cl 3.7 to 28.9), which is 2-fold higher than the risk among nonusers with factor VIII:C <150 IU/dL (odds ratio 5.3, 95% Cl 1.8 to 15.5).114 There is no indication that the simultaneous presence of high factor VIII and oral contraceptive use will result in an excess of thrombotic events (interaction).

Relationship Between High Factor VIII and Venous Thrombosis
The precise role of high factor VIII levels in defining venous thrombotic risk is still unknown. After its activation by thrombin, factor VIIIa dissociates from vWF to form a complex with factor IXa, which will result in marked acceleration of the activation of factor X.115 Activated factor X then converts prothrombin into thrombin, which in turn converts soluble fibrinogen into insoluble fibrin. It is possible that high factor VIII levels just increase the rate of thrombin and fibrin formation (in plasma, there is a large molar excess of factor IX over factor VIII).

Another possibility is that high factor VIII levels influence thrombotic risk via an effect on the APC sensitivity ratio (APCR). It has been shown that (in the absence of factor V Leiden) the thrombosis risk for the lowest quartile of normalized APCR (<0.92) is 4.4-fold higher than that for the highest quartile (>=1.05).116 For these measurements, "first-generation" APC-resistant tests were used (no dilution of the sample with factor V–deficient plasma). This explains the finding that high factor VIII levels are associated with a reduced sensitivity for APC in the absence of factor V Leiden (see FigureDown).107 117 118 After adjustment for factor VIII levels, the thrombosis risk associated with a normalized APCR <0.92 fell from 4.4- to 2.5-fold, indicating that factor VIII has a strong confounding effect on the thrombosis risk of a low APC ratio. Vice versa, it is also possible that high factor VIII exerts a thrombotic risk through the associated decreased responsiveness to APC. In all subjects of the Leiden Thrombophilia Study who do not have the factor V Leiden mutation, the thrombosis risk associated with factor VIII levels >=150 IU/dL is 4.8 (95% CI 3.1 to 7.5) compared with the risk associated with levels <100 IU/dL (Table 5Down). Entering normalized APCR as a continuous variable lowered the thrombosis risk of factor VIII levels >=150 IU/dL by 50%, to 2.7 (95% CI 1.6 to 4.7). Adjustment for age, blood group, and vWF did not change this risk estimate (odds ratio 2.4, 95% CI 1.2 to 5.2). Although high factor VIII remained an independent risk factor for thrombosis, these data show that adjustment for the APCR leads to attenuation of the risk of thrombosis. Therefore, it is possible that the risk of high factor VIII is at least partly mediated through an acquired APC resistance via a pathway that is independent of vWF and blood group.



View larger version (24K):
[in this window]
[in a new window]
  		Figure 1. Factor VIII:C and normalized APCR in 337 patients and 455 control subjects who do not have the factor V Leiden mutation.116 The figure shows a clear inverse correlation between factor VIII:C levels and the normalized APCR.


View this table:
[in this window]
[in a new window]
  		Table 5. ORs for Factor VIII:C Levels, Unadjusted and Adjusted for APCR (Without Factor V Leiden)


*    Should We Screen Patients With Thrombosis for High Factor VIII Levels?
up arrowTop
 up arrowIntroduction
 up arrowDeterminants of Plasma Factor...
 up arrowElevated Factor VIII Levels...
 *Should We Screen Patients...
down arrowConclusions
 down arrowReferences
 
An important question is whether we should screen patients with thrombosis for high factor VIII levels. High levels of factor VIII are a risk factor for a first thrombotic event, but high levels also seem to increase the risk of recurrences,109 which may indicate that sustained anticoagulant treatment is needed in these patients. When high factor VIII is included in a thrombophilia workup, we must make sure that testing for high factor VIII is reliable and that the individual’s risk of thrombosis is estimated correctly.

First, the assay of factor VIII itself may lead to considerable variation.119 Together with vWF:Ag, factor VIII:C showed the highest between-duplicate (5.6%) and between-day (15%) coefficients of variation. Most often, factor VIII is measured as factor VIII:C by using modifications of the activated partial thromboplastin time (1-stage assay). This 1-stage assay has the advantage of simplicity but can give falsely high results that are due to activation of the coagulation system during blood collection procedures and/or storage. Factor VIII:Ag can be measured by ELISA.108 The advantage of an ELISA (if properly designed) over the 1-stage assay is that it is not susceptible to activation of the coagulation system. The disadvantage of the ELISA is that it is more complicated to perform.

Furthermore, there is a large intraindividual variation in factor VIII levels, and finally, there is the important question of how we should interpret the result of a factor VIII measurement in terms of risk of a first thrombotic event and risk of recurrences. Should we use cutoff values? How should we handle in this context information on the presence of disease(s) that have been reported to be associated with high factor VIII levels (eg, malignancies)? Should we combine the result of the factor VIII measurement with information on vWF levels and blood group? Should we restrict the analysis to carriers of other risk factors of thrombosis? Still another problem is the timing of factor VIII measurement: during the acute thrombotic event, factor VIII levels may be elevated because of an acute phase reaction, and a reliable baseline value might not be obtained before several months. Taken together, there are still too many questions to be answered to recommend factor VIII measurement in routine thrombophilia screening.


*    Conclusions
up arrowTop
 up arrowIntroduction
 up arrowDeterminants of Plasma Factor...
 up arrowElevated Factor VIII Levels...
 up arrowShould We Screen Patients...
 *Conclusions
down arrowReferences
 
High levels of factor VIII are a risk factor for thrombosis, with a greater impact on venous than on arterial thrombosis. This risk is dose dependent for venous thrombosis, and factor VIII levels >=150 IU/dL account for 16% of all venous thrombotic events, whereas factor VIII levels>123 IU/dL explain 4% of all arterial events. High factor VIII levels may increase the risk of venous thrombosis via enhanced thrombin formation and/or through the induction of acquired APC resistance. The relationship between factor VIII and arterial thrombosis may be based on the combination of increased thrombin formation and increased platelet adhesion/aggregation, induced by vWF, at sites of arterial wall damage.

The molecular basis of high factor VIII levels is only partially known and consists of genetic and acquired factors. Blood group, acting through vWF levels, is an important genetic factor that explains {approx}30% of the variation in factor VIII levels. Attempts to find other genetic loci associated with high vWF and factor VIII levels have failed until now. It is likely that the largest part of high factor VIII levels is caused by a rise in vWF levels, which points to an increased synthesis or decreased clearance of the vWF–factor VIII complex. However, a substantial percentage of high factor VIII levels is not completely vWF-mediated and may point to genetically defined differences in the affinity of factor VIII for vWF.


*    Acknowledgments
 
This work was supported by a grant (No. 950-10-629) from the Netherlands Organization for Scientific Research (NWO). We thank Prof F.R. Rosendaal for his advice.

Received January 8, 2001; accepted February 14, 2001.


*    References
up arrowTop
 up arrowIntroduction
 up arrowDeterminants of Plasma Factor...
 up arrowElevated Factor VIII Levels...
 up arrowShould We Screen Patients...
 up arrowConclusions
 *References
 

  1. Virchow R. Phlogose und Thrombose im gefäßsystem: Gesammelte Abhandlungen zur Wissenschaftlichen Medizin. Frankfurt, Germany: Staatsdruckerei; 1856.
  2. Egeberg O. Inherited antithrombin III deficiency causing thrombophilia. Thromb Diath Haemorrh. 1965;13:516–530.
  3. Griffin JH, Evatt BL, Zimmerman TS, Kleiss AJ, Wideman C. Deficiency of protein C in congenital thrombotic disease. J Clin Invest. 1981;68:1370–1373.
  4. Allaart CF, Poort SR, Rosendaal FR, Reitsma PH, Bertina RM, Briët E. Increased risk of venous thrombosis in carriers of hereditary protein C deficiency defect. Lancet. 1993;341:134–138.[Medline] [Order article via Infotrieve]
  5. Schwarz HP, Fischer M, Hopmeier P, Batard MA, Griffin JH. Plasma protein S deficiency in familial thrombotic disease. Blood. 1984;64:1297–1300.[Abstract/Free Full Text]
  6. Koster T, Rosendaal FR, Briët E, Van Der Meer FJ, Colly LP, Trienekens PH, Poort SR, Reitsma PH, Vandenbroucke JP. Protein C deficiency in a controlled series of unselected outpatients: an infrequent but clear risk factor for venous thrombosis (Leiden Thrombophilia Study). Blood. 1995;85:2756–2761.[Abstract/Free Full Text]
  7. Rosendaal FR, Koster T, Vandenbroucke JP, Reitsma PH. High risk of thrombosis in patients homozygous for factor V Leiden (activated protein C resistance). Blood. 1995;85:1504–1508.[Abstract/Free Full Text]
  8. Poort SR, Rosendaal FR, Reitsma PH, Bertina RM. A common genetic variation in the 3'-untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and an increase in venous thrombosis. Blood. 1996;88:3698–3703.[Abstract/Free Full Text]
  9. Bertina RM, Koeleman BP, Koster T, Rosendaal FR, Dirven RJ, de Ronde H, van der Velden PA, Reitsma PH. Mutation in blood coagulation factor V associated with resistance to activated protein C. Nature. 1994;369:64–67.[Medline] [Order article via Infotrieve]
  10. Engesser L, Broekmans AW, Briët E, Brommer EJ, Bertina RM. Hereditary protein S deficiency: clinical manifestations. Ann Intern Med. 1987;106:677–682.
  11. Zöller B, Berntsdottes A, Garcia de Fructos P, Dahlbäck B. Resistance to activated protein C as the additional genetic risk factor in hereditary deficiency of protein S. Blood. 1995;85:3518–3523.[Abstract/Free Full Text]
  12. Koster T, Rosendaal FR, Reitsma PH, van der Velden PA, Briët E, Vandenbroucke JP. Factor VII and fibrinogen levels as risk factors for venous thrombosis: a case-control study of plasma levels and DNA polymorphisms: the Leiden Thrombophilia Study (LETS). Thromb Haemost. 1994;71:719–722.[Medline] [Order article via Infotrieve]
  13. Hughes GR. The anticardiolipin syndrome. Clin Exp Rheumatol. 1985;3:285–286.[Medline] [Order article via Infotrieve]
  14. den Heijer M, Koster T, Blom HJ, Bos GM, Briët E, Reitsma PH, Vandenbroucke JP, Rosendaal FR. Hyperhomocysteinemia as a risk factor for deep-vein thrombosis. N Engl J Med. 1996;334:759–762.[Abstract/Free Full Text]
  15. Meade TW, Mellows S, Brozovic M, Miller GJ, Chakrabarti RR, North WR, Haines AP, Stirling Y, Imeson JD, Thompson SG. Haemostatic function and ischaemic heart disease: principal results of the Northwick Park Heart Study. Lancet. 1986;2:533–537.[Medline] [Order article via Infotrieve]
  16. Hughes GRV. The antiphospholipid syndrome: ten years on. Lancet. 1993;342:341–344.[Medline] [Order article via Infotrieve]
  17. Boushey CJ, Beresford SAA, Omenn GS, Motnisky AG. A quantitative assessment of plasma homocysteine as a risk factor for vascular disease: probable benefits of increasing folic acid intake. JAMA. 1995;274:1049–1057.[Abstract]
  18. Rosendaal FR, Siscovick DS, Schwartz SM, Beverly RK, Psaty BM, Longstreth WT Jr, Raghunathan TE, Koepsell TD, Reitsma PH. Factor V Leiden (resistance to activated protein C) increases the risk of myocardial infarction in young women. Blood. 1997;89:2817–2821.[Abstract/Free Full Text]
  19. Doggen CJ, Cats VM, Bertina RM, Rosendaal FR. Interaction of coagulation defects and cardiovascular risk factors: increased risk of myocardial infarction associated with factor V Leiden or prothrombin 20210A. Circulation. 1998;97:1037–1041.[Abstract/Free Full Text]
  20. Rosendaal FR, Siscovick DS, Schwartz SM, Psaty BM, Raghunathan TE, Vos HL. A common prothrombin variant (20210 G to A) increases the risk of myocardial infarction in young women. Blood. 1997;90:1747–1750.[Abstract/Free Full Text]
  21. Longstreth WT Jr, Rosendaal FR, Siscovick DS, Vos HL, Schwartz SM, Psaty BM, Raghunathan TE, Koepsell TD, Reitsma PH. Risk of stroke in young women and two prothrombotic mutations: factor V Leiden and prothrombin gene variant (G20210A). Stroke. 1998;29:577–580.[Abstract/Free Full Text]
  22. Ridker PM, Hennekens CH, Lindpaintner K, Stampfer MJ, Eisenberg PR, Miletich JP. Mutation in the gene coding for coagulation factor V and the risk of myocardial infarction, stroke, and venous thrombosis in apparently healthy men. N Engl J Med. 1995;332:912–917.[Abstract/Free Full Text]
  23. Emmerich J, Poirier O, Evans A, Marques-Vidal P, Arveiler D, Luc G, Aiach M, Cambien F. Myocardial infarction, Arg 506 to Gln factor V mutation, and activated protein C resistance. Lancet. 1995;345:321.[Medline] [Order article via Infotrieve]
  24. Redondo M, Watzke HH, Stucki B, Sulzer I, Demarmels Biasiutti F, Binder BR, Furlan M, Lämmle B, Wuillemin WA. Coagulation factors II, V, VII, and X, prothrombin gene 20210G A transition, and factor V Leiden in coronary artery disease. Arterioscler Thromb Vasc Biol. 1999;19:1020–1025.[Abstract/Free Full Text]
  25. Ridker PM, Hennekens CH, Miletich JP. G20210A mutation in prothrombin gene and risk of myocardial infarction, stroke, and venous thrombosis in a large cohort of US men. Circulation. 1999;99:999–1004.[Abstract/Free Full Text]
  26. Croft SA, Daly ME, Steeds RP, Channer KS, Samani NJ, Hampton KK. The prothrombin 20210A allele and its association with myocardial infarction. Thromb Haemost. 1999;81:861–864.[Medline] [Order article via Infotrieve]
  27. Koster T, Blann AD, Briët E, Vandenbroucke JP, Rosendaal FR. Role of clotting factor VIII in effect of von Willebrand factor on occurrence of deep-vein thrombosis. Lancet. 1995;345:152–155.[Medline] [Order article via Infotrieve]
  28. Meijers JCM, Tekelenburg WLH, Bouma BN, Bertina RM, Rosendaal FR. High levels of coagulation factor XI as a risk factor for venous thrombosis. N Engl J Med. 2000;342:696–701.[Abstract/Free Full Text]
  29. van Hylckama Vlieg A, van der Linden IK, Bertina RM, Rosendaal FR. High levels of factor XI increase the risk of venous thrombosis. Blood. 2000;95:3678–3682.[Abstract/Free Full Text]
  30. O’Donnell J, Tuddenham EG, Manning R, Kemball-Cook G, Johnson D, Laffan M. High prevalence of elevated factor VIII levels in patients referred for thrombophilia screening: role of increased synthesis and relationship to the acute phase reaction. Thromb Haemost. 1997;77:825–828.[Medline] [Order article via Infotrieve]
  31. Kraaijenhagen RA, in’t Anker PS, Koopman MM, Reitsma PH, Prins MH, van den Ende A, Buller HR. High plasma concentration of factor VIIIc is a major risk factor for venous thromboembolism. Thromb Haemost. 2000;83:5–9.[Medline] [Order article via Infotrieve]
  32. Meade TW, Cooper JA, Stirling Y, Howarth DJ, Ruddock V, Miller GJ. Factor VIII, ABO blood group and the incidence of ischaemic heart disease. Br J Haematol. 1994;88:601–607.[Medline] [Order article via Infotrieve]
  33. Folsom AR, Wu KK, Rosamond WD, Sharrett AR, Chambless LE. Prospective study of hemostatic factors and incidence of coronary heart disease: the Atherosclerosis Risk in Communities (ARIC) Study. Circulation. 1997;96:1102–1108.[Abstract/Free Full Text]
  34. Folsom AR, Rosamond WD, Shahar E, Cooper LS, Aleksic N, Nieto FJ, Rasmussen ML, Wu KK. Prospective study of markers of hemostatic function with risk of ischemic stroke. Circulation. 1999;100:736–742.[Abstract/Free Full Text]
  35. Weiss HJ, Hoyer LW. Von Willebrand factor: dissociation from antihemophilic factor procoagulant activity. Science. 1973;182:1149–1151.[Abstract/Free Full Text]
  36. Wise RJ, Dorner AJ, Krane M, Pittman DD, Kaufman RJ. The role of von Willebrand factor multimerization and propeptide cleavage in the binding and stabilization of factor VIII. J Biol Chem. 1991;266:21948–21955.[Abstract/Free Full Text]
  37. Gill JC, Endres-Brooks J, Bauer PJ, Marks WJ Jr, Montgomery RR. The effect of ABO blood group on the diagnosis of von Willebrand disease. Blood. 1987;69:1691–1695.[Abstract/Free Full Text]
  38. Jeremic M, Weisert O, Gedde-Dahl TW. Factor VIII (AHG) levels in 1016 regular blood donors: the effects of age, sex, and ABO blood groups. Scand J Clin Lab Invest. 1976;36:461–466.[Medline] [Order article via Infotrieve]
  39. Ørstavik KH, Magnus P, Reisner H, Berg K, Graham JB, Nance W. Factor VIII and factor IX in a twin population: evidence for a major effect of ABO locus on factor VIII level. Am J Hum Genet. 1985;37:89–101.[Medline] [Order article via Infotrieve]
  40. Senis YA, Richardson M, Tinlin S, Maurice DH, Giles AR. Changes in the pattern of distribution of von Willebrand factor in rat aortic endothelial cells following thrombin generation in vivo. Br J Haematol. 1996;93:195–203.[Medline] [Order article via Infotrieve]
  41. Galbusera M, Zoja C, Donadelli R, Paris S, Morigi M, Benigni A, Figliuzzi M, Remuzzi G, Remuzzi A. Fluid shear stress modulates von Willebrand factor release from human vascular endothelium. Blood. 1997;90:1558–1564.[Abstract/Free Full Text]
  42. Kerr CB, Preston AE, Barr A, Biggs R. Further studies on the inheritance of factor 8. Br J Haematol.. 1966;12:212–233.[Medline] [Order article via Infotrieve]
  43. Veltkamp JJ, Mayo O, Motulsky AG, Fraser GR. Blood coagulation factors I, II, V, VII, VIII, IX, X, XI and XII in twins. Hum Hered. 1972;22:102–117.
  44. Filippi G, Mannucci PM, Coppola R, Farris A, Rinaldi A, Siniscalco M. Studies on hemophilia A in Sardinia bearing on the problems of multiple allelism, carrier detection, and differential mutation rate in the two sexes. Am J Hum Genet. 1984;36:44–71.[Medline] [Order article via Infotrieve]
  45. Souto JC, Almasy L, Borrell M, Gari M, Martinez E, Mateo J, Store WH, Blangero J, Fontcuberta J. Genetic determinants of hemostasis phenotypes in Spanish families. Circulation.. 2000;101:1546–1551.[Abstract/Free Full Text]
  46. Kamphuisen PW, Houwing-Duistermaat JJ, van Houwelingen HC, Eikenboom JC, Bertina RM, Rosendaal FR. Familial clustering of factor VIII and von Willebrand factor levels. Thromb Haemost. 1998;79:323–327.[Medline] [Order article via Infotrieve]
  47. Shima M, Fujimura Y, Nishiyama T, Tsujiuchi T, Narita N, Matsui T, Titani K, Katayama M, Yamamoto F, Yoshioka A. ABO blood group genotype and plasma von Willebrand factor in normal individuals. Vox Sang. 1995;68:236–240.[Medline] [Order article via Infotrieve]
  48. Souto JC, Almasy L, Muñiz-Diaz E, Soria JM, Borrell M, Beyén L, Mateo J, Madoz P, Stone W, Blangero J, et al. Functional effects of the ABO locus polymorphism on plasma levels of von Willebrand factor, factor VIII and activated partial thromboplastin time. Arterioscler Thromb Vasc Biol. 2000;20:2024–2028.[Abstract/Free Full Text]
  49. Sodetz JM, Paulson JC, McKee PA. Carbohydrate composition and identification of blood group A, B, and H oligosaccharide structures on human factor VIII/von Willebrand factor. J Biol Chem. 1979;254:10754–10760.[Free Full Text]
  50. Matsui T, Titani K, Mizuochi T. Structures of the asparagine-linked oligosaccharide chains of human von Willebrand factor: occurrence of blood group A, B, and H(O) structures. J Biol Chem. 1992;267:8723–8731.[Abstract/Free Full Text]
  51. Stoddart JH Jr, Andersen J, Lynch DC. Clearance of normal and type 2A von Willebrand factor in the rat. Blood. 1996;88:1692–1699.[Abstract/Free Full Text]
  52. Sodetz JM, Pizzo SV, McKee PA. Relationship of sialic acid to function and in vivo survival of human factor VIII/von Willebrand factor protein. J Biol Chem. 1977;252:5538–5546.[Free Full Text]
  53. Vlot AJ, Mauser-Bunschoten EP, Zarkova AG, Haan E, Kruitwagen CLJJ, Sixma JJ, van den Berg HM. The half-life of infused factor VIII is shorter in hemophiliac patients with blood group O than in those with blood group A. Thromb Haemost. 2000;83:65–69.[Medline] [Order article via Infotrieve]
  54. Morfini M, Mannucci PM, Tenconi PM, Longo G, Mazzuconi MG, Rodeghiero F, Ciavarella N, de Rosa V, Arter A. Pharmacokinetics of monoclonally-purified and recombinant factor VIII in patients with severe von Willebrand disease. Thromb Haemost. 1993;70:270–272.[Medline] [Order article via Infotrieve]
  55. O’Donnell J, Mumford A, Manning R, Laffan M. Elevation of FVIII:C in venous thromboembolism is persistent and independent of the acute phase response. Thromb Haemost. 2000;83:10–13.[Medline] [Order article via Infotrieve]
  56. Kamphuisen PW, Eikenboom JCJ, Vos HL, Pablo R, Sturk A, Bertina RM, Rosendaal FR. Increased levels of factor VIII and fibrinogen in patients with venous thrombosis are not caused by acute phase reactions. Thromb Haemost. 1999;81:680–683.[Medline] [Order article via Infotrieve]
  57. Kamphuisen PW, Lensen R, Houwing-Duistermaat JJ, Eikenboom JCJ, Harvey M, Bertina RM, Rosendaal FR. Heritability of elevated factor VIII antigen levels in factor V Leiden families with thrombophilia. Br J Haematol. 2000;109:519–522.[Medline] [Order article via Infotrieve]
  58. Hinney K, Shambeck CM, Haubitz I, Mansouri-Taleghani B, Wahler D, Keller F. High factor VIII levels represent a hereditary risk factor for venous thromboembolism. Thromb Haemost. 1999:864. Abstract.
  59. Mansvelt EPG, Laffan M, McVey JH, Tuddenham EGD. Analysis of the F8 gene in individuals with high plasma factor VIII:C levels and associated venous thrombosis. Thromb Haemost. 1998;80:561–565.[Medline] [Order article via Infotrieve]
  60. Kamphuisen PW. High Levels of Factor VIII and the Risk of Venous Thrombosis [PhD thesis]. Leiden, the Netherlands: Leiden University; 2000.
  61. Keightley AM, Lam YM, Brady JN, Cameron CL, Lillicrap D. Variation at the von Willebrand factor (vWF) gene locus is associated with plasma vWF:Ag levels: identification of three novel single nucleotide polymorphisms in the vWF gene promoter. Blood. 1999;93:4277–4283.[Abstract/Free Full Text]
  62. Balleisen L, Bailey J, Epping PH, Schulte H, van de Loo J. Epidemiological study on factor VII, factor VIII and fibrinogen in an industrial population, I: baseline data on the relation to age, gender, body-weight, smoking, alcohol, pill-using, and menopause. Thromb Haemost. 1985;54:475–479.[Medline] [Order article via Infotrieve]
  63. Conlan MG, Folsom AR, Finch A, Davis CE, Sorlie P, Marcucci G, Wu KK. Associations of factor VIII and von Willebrand factor with age, race, sex, and risk factors for atherosclerosis: the Atherosclerosis Risk in Communities (ARIC) Study Thromb Haemost. 1993;70:380–385.[Medline] [Order article via Infotrieve]
  64. Cushman M, Yanez D, Psaty BM, Fried LP, Heiss G, Lee M, Polak JF, Savage PJ, Tracy RP. Association of fibrinogen and coagulation factors VII and VIII with cardiovascular risk factors in the elderly: the Cardiovascular Health Study: Cardiovascular Health Study Investigators. Am J Epidemiol. 1996;143:665–676.[Abstract/Free Full Text]
  65. Bloemenkamp KWM, Rosendaal FR, Helmerhorst FM, Koster T, Bertina RM, Vandenbroucke JP. Hemostatic effects of oral contraceptives in women who developed deep-vein thrombosis while using oral contraceptives. Thromb Haemost. 1998;80:382–387.[Medline] [Order article via Infotrieve]
  66. Kopitsky RG, Switzer ME, Williams RS, McKee PA. The basis for the increase in factor VIII procoagulant activity during exercise. Thromb Haemost. 1983;49:53–57.[Medline] [Order article via Infotrieve]
  67. Small M, Tweddel AC, Rankin AC, Lowe GD, Prentice CR, Forbes CD. Blood coagulation and platelet function following maximal exercise: effects of beta-adrenoceptor blockade. Haemostasis. 1984;14:262–268.[Medline] [Order article via Infotrieve]
  68. Cash JD, Allan AG. The fibrinolytic response to moderate exercise and intravenous adrenaline in the same subjects. Br J Haematol. 1967;13:376–383.[Medline] [Order article via Infotrieve]
  69. Ingram GI, Knights SF, Barrow EM, Dejanov II. The rise in factor-8 concentration after infusion of adrenaline. Br J Haematol. 1968;15:326.
  70. Ingram GI, Jones RV. The rise in clotting factor 8 induced in man by adrenaline: effect of alpha- and beta-blockers. J Physiol (Lond). 1966;187:447–454.[Abstract/Free Full Text]
  71. Jilma B, Dirnberger E, Eichler HG, Matulla B, Schmetterer L, Kapiotis S, Speiser W, Wagner OF. Partial blockade of nitric oxide synthase blunts the exercise-induced increase of von Willebrand factor antigen and of factor VIII in man. Thromb Haemost. 1997;78:1268–1271.[Medline] [Order article via Infotrieve]
  72. Kaufmann JE, Oksche A, Wolheim CB, Günther G, Rosenthal W, Vischer UM. Vasopressin-induced von Willebrand factor secretion from endothelial cells involve V2 receptors and cAMP. J Clin Invest. 2000;106:107–116.[Medline] [Order article via Infotrieve]
  73. Holmberg L, Nilsson IM. AHF related protein in clinical praxis. Scand J Haematol. 1974;12:221–231.[Medline] [Order article via Infotrieve]
  74. Bloom AL. The biosynthesis of factor VIII. Clin Haematol. 1979;8:53–77.[Medline] [Order article via Infotrieve]
  75. Ginsburg D. Molecular genetics of von Willebrand disease. Thromb Haemost. 1999;82:585–591.[Medline] [Order article via Infotrieve]
  76. Mohlke KL, Purkayastha AA, Westrick RJ, Smith PL, Petryniak B, Lowe JB, Ginsburg D. MvWF, a dominant modifier of murine von Willebrand factor, results from altered lineage-specific expression of a glycosyl transferase. Cell. 1999;96:111–120.[Medline] [Order article via Infotrieve]
  77. Levy G, Mohlke KL, Ginsburg D. MvWF2, a second modifier gene for mouse von Willebrand factor levels, maps to mouse chromosome 10. Blood. 2000;96:532a. Abstract.
  78. Nichols WC, Seligsohn U, Zivelin A, Terry VH, Hertel CE, Wheatley MA, Moussalli MJ, Hauri HP, Ciavarella N, Kaufman RJ, et al. Mutations in the ER-Golgi intermediate compartment protein ERGIC-53 cause combined deficiency of coagulation factors V and VIII. Cell. 1998;93:61–70.[Medline] [Order article via Infotrieve]
  79. Nichols WC, Seligsohn U, Zivelin A, Terry VH, Arnold ND, Siemieniak DR, Kaufman RJ, Ginsburg D. Linkage of combined factors V and VIII deficiency to chromosome 18q by homozygosity mapping. J Clin Invest. 1997;99:596–601.[Medline] [Order article via Infotrieve]
  80. Neerman-Arbez M, Antonarakis SE, Blouin JL, Zeinali S, Akhtari M, Afshar Y, Tuddenham EG. The locus for combined factor V-factor VIII deficiency (F5F8D) maps to 18q21, between D18S849 and D18S1103. Am J Hum Genet. 1997;61:143–150.[Medline] [Order article via Infotrieve]
  81. Kamphuisen PW, Rosendaal FR, Eikenboom JCJ, Bos R, Bertina RM. Factor V antigen levels and venous thrombosis: risk profile, interaction with factor V Leiden and relation with factor VIII:Ag levels. Arterioscler Thromb Vasc Biol. 2000;20:1382–1386.[Abstract/Free Full Text]
  82. Rosendaal FR, Varekamp I, Smit C, Bröcker-Vriends AH, van Dijck H, Vandenbroucke JP, Hermans J, Suurmeijer TP, Briët E. Mortality and causes of death in Dutch haemophiliacs, 1973–86. Br J Haematol. 1989;71:71–76.[Medline] [Order article via Infotrieve]
  83. Triemstra M, Rosendaal FR, Smit C, Van der Ploeg HM, Briët E. Mortality in patients with hemophilia: changes in a Dutch population from 1986 to 1992 and 1973 to 1986. Ann Intern Med. 1995;123:823–827.[Abstract/Free Full Text]
  84. Kernoff LM, Rose AG, Hughes J, Jacobs P. Autopsy findings in an elderly man suffering from severe von Willebrand’s disease. Thromb Haemost. 1981;46:714–716.[Medline] [Order article via Infotrieve]
  85. Federici AB, Mannucci PM, Fogato E, Ghidoni P, Matturri L. Autopsy findings in three patients with von Willebrand disease type IIB and type III: presence of atherosclerotic lesions without occlusive arterial thrombi. Thromb Haemost. 1993;70:758–761.[Medline] [Order article via Infotrieve]
  86. Nichols TC, Bellinger DA, Reddick RL, Smith SV, Koch GC, Davis K, Sigman J, Brinkhous KM, Griggs TR, Read MS. The roles of von Willebrand factor and factor VIII in arterial thrombosis: studies in canine von Willebrand disease and hemophilia A. Blood. 1993;81:2644–2651.[Abstract/Free Full Text]
  87. Egeberg O. Clotting factor levels in patients with coronary atherosclerosis. Scand J Clin Lab Invest. 1962;14:253–258.[Medline] [Order article via Infotrieve]
  88. Allan TM, Dawson AA. ABO blood groups and ischaemic heart disease in men. Br Heart J. 1968;30:377–382.[Free Full Text]
  89. Bronte-Steward B, Botha MC, Krut LH. ABO blood groups in relation to ischaemic heart disease. BMJ. 1962;1:1646–1650.
  90. Gertler MM, White PD. Coronary Heart Disease in Young Adults. Cambridge, Mass: Harvard University Press; 1954:18–21.
  91. Stormorker H, Erikssen J. Plasma antithrombin III and factor VIII antigen in relation to angiographic findings, aging and blood groups in middle-aged men. Thromb Haemost. 1977;38:874–880.[Medline] [Order article via Infotrieve]
  92. Rice GI, Grant PJ. Factor VIII coagulant activity and antigen in subjects with ischaemic heart disease. Thromb Haemost. 1998;80:757–762.[Medline] [Order article via Infotrieve]
  93. Tracy RP, Arnold AM, Ettinger W, Fried L, Meilahn E, Savage P. The relationship of fibrinogen and factors VII and VIII to incident cardiovascular disease and death in the elderly. Arterioscler Thromb Vasc Biol. 1999;19:1776–1783.[Abstract/Free Full Text]
  94. Thompson SG, Kienast J, Pyke SD, Haverkate F, van de Loo JC. Hemostatic factors and the risk of myocardial infarction or sudden death in patients with angina pectoris: European Concerted Action on Thrombosis and Disabilities Angina Pectoris Study Group. N Engl J Med. 1995;332:635–641.[Abstract/Free Full Text]
  95. Rumley A, Lowe GD, Sweetnam PM, Yarnell JWG, Ford RP. Factor VIII, von Willebrand factor and the risk of major ischaemic heart disease in the Caerphilly Heart Study. Br J Haematol. 1999;105:110–116.[Medline] [Order article via Infotrieve]
  96. Catto AJ, Carter AM, Barrett JH, Bamford J, Rice PJ, Grant PJ. Von Willebrand factor and factor VIII:C in acute cerebrovascular disease: relationship to stroke subtype and mortality. Thromb Haemost. 1997;77:1104–1108.[Medline] [Order article via Infotrieve]
  97. Greenland S. Applications of stratified analysis methods. In: Greenland S, Rothman KJ, eds. Modern Epidemiology. 2nd ed. Philadelphia, Pa: Lippincott-Raven; 1998:295–297.
  98. Jager A, van Hinsbergh VWM, Kostense PJ, Emeis JJ, Yudkin JS, Nijpels G, Dekker JM, Heine RJ, Bouter LM, Stehouwer CDA. Von Willebrand factor, C-reactive protein, and 5-year mortality in diabetic and non-diabetic subjects. Arterioscler Thromb Vasc Biol. 1999;19:3071–3078.[Abstract/Free Full Text]
  99. Blann A. Von Willebrand factor and the endothelium in vascular disease. Br J Biomed Sci. 1993;50:125–134.[Medline] [Order article via Infotrieve]
  100. Pottinger BE, Read RC, Paleolog EM, Higgins PG, Pearson JD. Von Willebrand factor is an acute phase reactant in man. Thromb Res. 1989;53:387–394.[Medline] [Order article via Infotrieve]
  101. Ruggeri ZM. Von Willebrand factor. J Clin Invest. 1997;99:559–564.[Medline] [Order article via Infotrieve]
  102. Badimon L, Badimon JJ, Chesebro JH, Fuster V. Von Willebrand factor and cardiovascular disease. Thromb Haemost. 1993;70:111–118.[Medline] [Order article via Infotrieve]
  103. Kingsbury KJ. Relation of ABO blood-groups to atherosclerosis. Lancet. 1971;1:199–203.[Medline] [Order article via Infotrieve]
  104. Medalie JH, Levene C, Papier C, Goldbourt U, Dreyfuss F, Oron D, Neufeld H, Riss E. Blood groups, myocardial infarction and angina pectoris among 10.000 adult males. N Engl J Med. 1971;285:1348–1353.
  105. Folsom AR, Wu KK, Shahar E, Davis CE. Association of hemostatic variables with prevalent cardiovascular disease and asymptomatic carotid artery atherosclerosis. Arterioscler Thromb. 1993;13:1829–1836.[Abstract/Free Full Text]
  106. Jick H, Slone D, Westerholm B. Venous thromboembolic disease and ABO blood type. Lancet. 1969;1:539–542.[Medline] [Order article via Infotrieve]
  107. Preston AE, Barr A. The plasma concentration of factor VIII in the normal population, II: the effects of age, sex and blood group. Br J Hae