Screening for thrombophilia in high-risk situations: a meta-analysis and cost-effectiveness analysis

Venous Thromboembolism in Pregnancy: A Review of Diagnosis, Management, and Prevention

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism, is a leading cause of maternal morbidity and mortality worldwide. Physiological changes that occur in a normal pregnancy increase the risk for VTE by 4-5-fold in the antepartum period and 30-60-fold in the immediate postpartum period. Compressive ultrasonography is the diagnostic test of choice for deep vein thrombosis. Both ventilation/perfusion scanning and computed tomography pulmonary angiography can reliably diagnose pulmonary embolism. Anticoagulation for a minimum of 3 months, typically with low molecular weight heparin, is the treatment of choice for pregnancy-associated VTE (PA-VTE). Despite the significant societal burden and potentially devastating consequences, there is a paucity of data surrounding the prevention of PA-VTE, resulting in major variations between international guidelines. This review will summarize the current recommendations for diagnosis, management, and prevention of PA-VTE.

Thromboprophylaxis during pregnancy and the puerperium: a systematic review and economic evaluation to estimate the value of future research

Background

Pharmacological prophylaxis to prevent venous thromboembolism is currently recommended for women assessed as being at high risk of venous thromboembolism during pregnancy or in the 6 weeks after delivery (the puerperium). The decision to provide thromboprophylaxis involves weighing the benefits, harms and costs, which vary according to the individual's venous thromboembolism risk. It is unclear whether the United Kingdom's current risk stratification approach could be improved by further research.

Objectives

To quantify the current decision uncertainty associated with selecting women who are pregnant or in the puerperium for thromboprophylaxis and to estimate the value of one or more potential future studies that would reduce that uncertainty, while being feasible and acceptable to patients and clinicians.

Methods

A decision-analytic model was developed which was informed by a systematic review of risk assessment models to predict venous thromboembolism in women who are pregnant or in the puerperium. Expected value of perfect information analysis was used to determine which factors are associated with high decision uncertainty and should be the target of future research. To find out whether future studies would be acceptable and feasible, we held workshops with women who have experienced a blood clot or have been offered blood-thinning drugs and surveyed healthcare professionals. Expected value of sample information analysis was used to estimate the value of potential future research studies.

Results

The systematic review included 17 studies, comprising 19 unique externally validated risk assessment models and 1 internally validated model. Estimates of sensitivity and specificity were highly variable ranging from 0% to 100% and 5% to 100%, respectively. Most studies had unclear or high risk of bias and applicability concerns. The decision analysis found that there is substantial decision uncertainty regarding the use of risk assessment models to select high-risk women for antepartum prophylaxis and obese postpartum women for postpartum prophylaxis. The main source of decision uncertainty was uncertainty around the effectiveness of thromboprophylaxis for preventing venous thromboembolism in women who are pregnant or in the puerperium. We found that a randomised controlled trial of thromboprophylaxis in obese postpartum women is likely to have substantial value and is more likely to be acceptable and feasible than a trial recruiting women who have had a previous venous thromboembolism. In unselected postpartum women and women following caesarean section, the poor performance of risk assessment models meant that offering prophylaxis based on these models had less favourable cost effectiveness with lower decision uncertainty.

Limitations

The performance of the risk assessment model for obese postpartum women has not been externally validated.

Conclusions

Future research should focus on estimating the efficacy of pharmacological thromboprophylaxis in pregnancy and the puerperium, and clinical trials would be more acceptable in women who have not had a previous venous thromboembolism.

Study registration

This study is registered as PROSPERO CRD42020221094.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR131021) and is published in full in Health Technology Assessment; Vol. 28, No. 9. See the NIHR Funding and Awards website for further award information.

Do we need more guidance on thrombophilia testing? Challenges and special considerations

INTRODUCTION

Thrombophilia testing (TT) is a laboratory procedure designed to detect the risk factors involved in the pathogenesis of vascular occlusions. The role of TT is also controversial because it has a limited impact on the choice and duration of antithrombotic treatments.

AREAS COVERED

We reviewed, by examining MEDLINE up to October 2023. Accepted and not accepted thrombophilia markers are discussed along with the appropriateness or not of prescribing TT in several conditions such as: provoked and unprovoked venous thromboembolism (VTE), women who are planning a pregnancy whose relatives had VTE or have a hereditary thrombophilia, before assumption of estro-progestins, after multiple pregnant loss, arterial thrombosis, retinal vein occlusion, and splanchnic vein thrombosis.

EXPERT OPINION

TT is not essential in the management of VTE, but it may be useful for limiting adverse events in case of thrombophilia. We expose our criticism of items afforded by other guidelines by presenting our opinion based on both the scientific evidence and clinical practice. We also deal with common mistakes in prescribing and interpretations of TT hoping to purpose an educational approach on this topic. Finally, we emphasize the creation of the expert in hemostasis and thrombosis who should be present in every hospital.

Hemostatic considerations for gender affirming care

Gender dysphoria or gender incongruence is defined as "persons that are not satisfied with their designated gender" [1]. The awareness and evidence-based treatment options available to this population have grown immensely over the last two decades. Protocols now include an Endocrine Society Clinical Practice Guideline [1] as well as the World Professional Association of Transgender Health Standards of Care (WPATH SOC) [2]. Hematologic manifestations, most notably thrombosis, are one of the most recognized adverse reactions to the hormones used for gender-affirming care. Therefore, hematologists are frequently consulted prior to initiation of hormonal therapy to help guide safe treatment. This review will focus on the scientific evidence related to hemostatic considerations for various gender-affirming therapies and serve as a resource to assist in medical decision-making among providers and patients.

Cardiovascular disease and feminizing gender-affirming hormone therapy: Implications for the provision of safe and lifesaving care

Sex recorded at birth, gender identity, and feminizing gender-affirming hormone therapy (fGAHT) likely contribute to cardiovascular disease (CVD) risk in transgender women. Understanding the interplay of these factors is necessary for the provision of safe, affirming, and lifesaving care. Among transgender women taking fGAHT, data show increases in CVD mortality and rates of myocardial infarction, stroke, and venous thromboembolism compared to reference populations, depending on study design and comparators. However, most studies are observational with a paucity of contextualizing information (e.g., dosing, route of administration, gonadectomy status), which makes it difficult to parse adverse fGAHT effects from confounders and interaction with known CVD risk factors (e.g., obesity, smoking, psychosocial and gender minority stressors). Increased CVD risk in transgender women points toward a need for greater attention to CVD management in this population including cardiology referral when indicated and additional research on the mechanisms and mediators of CVD risk.

Approach to Thrombophilia in Pregnancy-A Narrative Review

Thrombophilia is a genetic predisposition to hypercoagulable states caused by acquired haemostasis conditions; pregnancy causes the haemostatic system to become hypercoagulable, which grows throughout the pregnancy and peaks around delivery. Genetic testing for thrombophilic gene mutations is evaluated using different methodologies of real-time polymerase chain reaction and DNA microarrays of specific genes. Adapting the general care of the pregnant woman to the particularities caused by thrombophilia is an important component, so screening is preferred to assess the degree of genetic damage that manifests itself as a risk of thrombosis. The major goal of this narrative review was to quantitatively evaluate the literature data on the specific care of pregnant women with thrombophilia that are at risk of developing unplanned miscarriages.

Lateral sinus thrombosis in a young patient with sudden neurosensorial hearing loss and genetic thrombophilia: A case report

Sensorineural hearing loss (SSHL) with a sudden onset is frequently encountered as a medical emergency in the ear, nose and throat (ENT) practice. The exact pathophysiology of the disease remains unknown, with the most likely etiologies being viral infection, inflammation, drug toxicity, trauma, or autoimmune response. Even though thrombophilia and cerebrovascular complications may lead, among others, to sudden neurosensorial hearing loss, its diagnosis is most often made following the onset of thrombotic complications. A case of a young female patient with unknown congenital hypercoagulation status complicated with lateral sinus thrombosis and unilateral drug-induced reversible hearing loss is presented. Molecular testing confirmed the diagnosis of genetic thrombophilia, due to the homozygous V Leiden, homozygous MTHFR A1298C, and heterozygous MTHFR C677T mutations. Although hereditary thrombophilia is a well-known topic in medical practice, current guidelines require continuous improvement, especially among patients treated in departments where this pathology is more difficult to recognize and manage.

Venous thromboembolism prophylaxis for women at risk during pregnancy and the early postnatal period

BACKGROUND

Venous thromboembolism (VTE), although rare, is a major cause of maternal mortality and morbidity. Some women are at increased risk of VTE during pregnancy and the early postnatal period (e.g. caesarean section, family history of VTE, or thrombophilia), and so prophylaxis may be considered. As some methods of prophylaxis carry risks of adverse effects, and risk of VTE is often low, benefits of thromboprophylaxis may be outweighed by harms.

OBJECTIVES

To assess the effects of thromboprophylaxis during pregnancy and the early postnatal period on the risk of venous thromboembolic disease and adverse effects in women at increased risk of VTE.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (18 October 2019). In addition, we searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) for unpublished, planned and ongoing trial reports (18 October 2019).

SELECTION CRITERIA

Randomised trials comparing one method of thromboprophylaxis with placebo or no treatment, or two (or more) methods of thromboprophylaxis.

DATA COLLECTION AND ANALYSIS

At least two review authors assessed trial eligibility, extracted data, assessed risk of bias, and judged certainty of evidence for selected critical outcomes (using GRADE). We conducted fixed-effect meta-analysis and reported data (all dichotomous) as summary risk ratios (RRs) with 95% confidence intervals (CIs).

MAIN RESULTS

Twenty-nine trials (involving 3839 women), overall at moderate to high risk of bias were included. Trials were conducted across the antenatal, peripartum and postnatal periods, with most in high-income countries. Interventions included types and regimens of heparin (low molecular weight heparin (LMWH) and unfractionated heparin (UFH)), hydroxyethyl starch (HES), and compression stockings or devices. Data were limited due to a small number of trials in comparisons and/or few or no events reported. All critical outcomes (assessed for comparisons of heparin versus no treatment/placebo, and LMWH versus UFH) were considered to have very low-certainty evidence, downgraded mainly for study limitations and imprecise effect estimates.  Maternal death was not reported in most studies. Antenatal (± postnatal) prophylaxis For the primary outcomes symptomatic thromboembolic events pulmonary embolism (PE) and/or deep vein thrombosis (DVT), and the critical outcome of adverse effects sufficient to stop treatment, the evidence was very uncertain.  Symptomatic thromboembolic events: - heparin versus no treatment/placebo (RR 0.39; 95% CI 0.08 to 1.98; 4 trials, 476 women; very low-certainty evidence); - LMWH versus UFH (RR 0.47; 95% CI 0.09 to 2.49; 4 trials, 404 women; very low-certainty evidence); Symptomatic PE: - heparin versus no treatment/placebo (RR 0.33; 95% CI 0.02 to 7.14; 3 trials, 187 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 287 women); Symptomatic DVT: - heparin versus no treatment/placebo (RR 0.33; 95% CI 0.04 to 3.10; 4 trials, 227 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 287 women); Adverse effects sufficient to stop treatment: - heparin versus no treatment/placebo (RR 0.49; 95% CI 0.05 to 5.31; 1 trial, 139 women; very low-certainty evidence); - LMWH versus UFH (RR 0.07; 95% CI 0.01 to 0.54; 2 trials, 226 women; very low-certainty evidence). Peripartum/postnatal prophylaxis Vaginal or caesarean birth When UFH and no treatment were compared, the effects on symptomatic thromboembolic events (RR 0.16; 95% CI 0.02 to 1.36; 1 trial, 210 women; very low-certainty evidence), symptomatic PE (RR 0.16; 95% CI 0.01 to 3.34; 1 trial, 210 women; very low-certainty evidence), and symptomatic DVT  (RR 0.27; 95% CI 0.03 to 2.55; 1 trial, 210 women; very low-certainty evidence) were very uncertain.  Maternal death and adverse effects sufficient to stop treatment were not reported. Caesarean birth Symptomatic thromboembolic events: - heparin versus no treatment/placebo (RR 1.30; 95% CI 0.39 to 4.27; 4 trials, 840 women; very low-certainty evidence); - LMWH versus UFH (RR 0.33; 95% CI 0.01 to 7.99; 3 trials, 217 women; very low-certainty evidence); Symptomatic PE: - heparin versus no treatment/placebo (RR 1.10; 95% CI 0.25 to 4.87; 4 trials, 840 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 217 women);  Symptomatic DVT: - heparin versus no treatment/placebo (RR 1.30; 95% CI 0.24 to 6.94; 5 trials, 1140 women; very low-certainty evidence); LMWH versus UFH (RR 0.33; 95% CI 0.01 to 7.99; 3 trials, 217 women; very low-certainty evidence); Maternal death: - heparin versus placebo (no events, 1 trial, 300 women); Adverse effects sufficient to stop treatment: - heparin versus placebo (no events;  1 trial, 140 women). Postnatal prophylaxis No events were reported for LMWH versus no treatment/placebo for: symptomatic thromboembolic events, symptomatic PE and symptomatic DVT (all 2 trials, 58 women), or maternal death (1 trial, 24 women). Adverse effects sufficient to stop treatment were not reported. We were unable to conduct subgroup analyses due to lack of data. Sensitivity analysis including the nine studies at low risk of bias did not impact overall findings.

AUTHORS' CONCLUSIONS

The evidence is very uncertain about benefits and harms of VTE thromboprophylaxis in women during pregnancy and the early postnatal period at increased risk of VTE. Further high-quality very large-scale randomised trials are needed to determine effects of currently used treatments in women with different VTE risk factors. As sufficiently large definitive trials are unlikely to be funded, secondary data analyses based on high-quality registry data are important.

Thrombophilia screening revisited: an issue of personalized medicine

Clinical thrombophilia is the consequence of multiple gene and/or environment interactions. Thrombophilia screening requires a targeted patient with specific indication, in which a finding would have implications. Carrying out a thrombophilia examination in the physician's practice is often a cause of uncertainty and concern. The concerns begin in choosing the right patient to be examined, are associated with the time of investigation, with the choice of analysis, the test-material and with the correct interpretation of the results. Difficulties, which can influence the results, can occur with both organization and blood sampling. As common for any analysis, pre-analytical, analytical and post-analytical factors should be considered, as well as the possibility of false positive or false negative results. Finally, recommendation of correct therapeutic and prophylactic measures for the patient and his relatives is an additional focus. In this article we want to provide-on the basis of the evidence and personal experience-the theory of thrombophilia-investigation, the indications for testing, as well as practical recommendations for treatment options.

Clinical Utilization and Cost of Thrombophilia Testing in Patients with Venous Thromboembolism

Introduction  Testing for inherited and acquired thrombophilias adds to the cost of care of patients with venous thromboembolism (VTE), though results may not influence patient management.

Methods  This is a single-center, retrospective study conducted at Emory University Hospitals from January to December 2015 to (1) determine the pattern of thrombophilia testing in patients with VTE, (2) study the impact of results of thrombophilia testing on clinical decision-making, and (3) determine the direct costs of thrombophilia testing in patients with VTE.

Results  Of the 266 eligible patients, 189 (71%) underwent testing; 51 (26.9%) tested positive and the results impacted management in 32 (16.9%) of tested patients. Patient undergoing testing were more likely to be younger than 40 years (30.9 vs. 18.2%), have had prior pregnancy loss (9.0 vs. 0%), or known family history of hypercoagulability (24.9 vs. 10.4%), and were less likely to have had provoked VTE (37 vs. 79.2%). The most common thrombophilias tested were antiphospholipid syndrome (60.1%), factor V Leiden (59.7%), and prothrombin gene mutation (57.5%). Direct costs of thrombophilia testing were $2,364.32 per patient, $12,331.55 to diagnose 1 positive, and $19,653.41 per patient-management affected.

Conclusion  We noted significant variability in selection of patients and panel of tests, sparse utilization of test results in patient management, but high cost associated with thrombophilia testing in patients with VTE. With guidelines advocating selective use of thrombophilia testing and attention to potential impact of test results in patient management, we propose the need for measures at institutional levels to improve test-ordering practices.

Guidelines for superficial venous thrombosis

Superficial venous thrombosis (SVT) or superficial thrombophlebitis is characterized by thrombi within superficial veins, with partial involvement or occlusion of the lumen and inflammatory reaction along the course of the vein. Clinical diagnosis tends to be straightforward, but supplementary tests and examinations are needed to confirm thrombosis extension and possible thromboembolic complications. SVT can be associated with deep venous thrombosis in 6 to 40% of cases, with asymptomatic pulmonary embolism (PE) in 20 to 33%, and with symptomatic PE in 2 to 13%. Despite the morbidity and complications, there are currently no Brazilian guidelines for SVT. These guidelines cover the most important issues related to SVT definition, terminology, and etiology, and set out recommendations for diagnosis and treatment.

Transgender patients and the role of the coagulation clinician

The medical care of transgender patients relies on the use of sex hormones to develop and maintain the physical characteristics consistent with gender identity as the first step in transitioning. Hormonal therapy is usually continued indefinitely, even following gender-affirming surgeries. The use of hormonal treatments is associated with a multitude of positive effects as well as complications and side effects. The risk of venous thromboembolism (VTE) is a major concern. Transgender patients are often referred to coagulation specialists for advice regarding an individual patient's risk for VTE, especially if there is a personal or family history of VTE. Coagulation specialists need to be familiar with endocrine therapy including the goals of treatment and the VTE risks associated with currently used hormone regimens. We will review common referral questions and the available data and their limitations for the use of hormonal therapy in transgender patients focusing on the risk of VTE.

Venous Thromboembolism: Role of the Clinical Laboratory in Diagnosis and Management

Background

Venous thromboembolism (VTE) is the third most common cause of cardiovascular illness and is projected to double in incidence by 2050. It is a spectrum of disease that includes deep venous thrombosis (DVT) and pulmonary embolism (PE). In February 2016, the American College of Chest Physicians provided updated management guidelines for DVT and PE to address some of the unresolved questions from the previous version and to provide recommendations related to newer anticoagulants.

Content

Here we review current concepts for screening, diagnosis, thromboprophylaxis, and management of DVT and PE. We also describe the management of VTE in acute, long-term, and extended phases of treatment. Thrombophilia testing is rarely necessary and should be used judiciously; the laboratory can serve an important role in preventing unnecessary testing. The direct oral anticoagulants are as effective as conventional treatment and are preferred agents except in the case of cancer. The initial management of PE should be based on risk stratification including the use of D-dimer testing. Thrombolysis is used in cases of hemodynamically unstable PE and not for low-risk patients who can be treated on an outpatient basis.

Summary

This review is intended to provide readers with updated guidelines for screening, testing, prophylaxis, and management from various organizations.

Re-Examining Genetic Screening and Oral Contraceptives: A Patient-Centered Review

The World Health Organization classifies combined hormonal contraception as an unacceptable health risk in the presence of a known thrombogenic mutation but advises against routine thrombophilia screening before initiating combined oral contraceptives (COCs) on the grounds of high screening costs and low prevalence. From the perspective of patient-centered care, we examine cost, prevalence, and other published arguments for and against thrombophilia screening before initiating COCs. Our patient-centered review draws on relevant empirical evidence concerning the advantages and disadvantages of thrombophilia screening, while placing the discussion in the broader context of evolving attitudes toward genetic testing and a shifting policy landscape that provides many women direct access to COCs and/or thrombophilia screening. Given variation in prior probabilities of thrombophilia, expected exposure to other risk factors for venous thromboembolism, attitudes towards risk, expected reactions to a positive test result, ability to pay, and concerns about genetic discrimination, we conclude that the current one-size-fits-most approach is not consistent with patient-centered care. Instead, we advocate for greater patient and provider education concerning the implications of thrombophilia screening. Moreover, we recommend offering patients optional thrombophilia screening before initiating COCs.

Testosterone Therapy, Thrombophilia, Venous Thromboembolism, and Thrombotic Events

In our sequential studies of 67 and 21 patients, testosterone therapy (TT) interacted with thrombophilia⁻hypofibrinolysis, leading to venous thromboembolism (VTE). Compared to 111 VTE controls not taking TT (VTE-no TT), the 67 and 21 cases were more likely (p < 0.05 for all) to have Factor V Leiden (FVL) heterogeneity (24% and 33% vs. 12%), the lupus anticoagulant (14% and 33% vs. 4%), and high lipoprotein(a) (33% vs. 13%, n = 21). After a first VTE and continuing TT, 11 thrombophilic cases had a second VTE despite adequate anticoagulation, 6 of whom, still anticoagulated, had a third VTE. The greatest density of thrombotic events was at three months after starting TT, with a rapid decline by 10 months. From <1 to 8 months after starting TT, 65% of VTE occurred, which may reflect TT-induced depletion of susceptible thrombophilic patients, leaving a winnowed residual group with fewer VTE events despite the continuation of TT. Before starting TT, we suggest screening for FVL, lipoprotein(a), and the lupus anticoagulant to identify patients at increased VTE risk, with an adverse risk-to-benefit ratio for TT. We suggest that TT should not be started in patients with known thrombophilia⁻hypofibrinolysis, and should not be continued after a first VTE. When TT is given to patients with thrombophilia⁻hypofibrinolysis, VTE may occur and then recur despite adequate anticoagulation.

Hypercoagulable states in arterial and venous thrombosis: When, how, and who to test?

Evaluation for underlying hypercoagulable states in patients with thrombosis is a frequent clinical conundrum. Testing for thrombophilias is often reflexively performed without strategic approach nor clear appreciation of the clinical implications of such results. Guidelines vary in the appropriate utilization of thrombophilia testing. In this review, we discuss the more commonly encountered inherited and acquired thrombophilias, their association with initial and recurrent venous thromboembolism, arterial thromboembolism, and role in women's health. We suggest an approach to thrombophilia testing guided by the clinical presentation, suspected pathophysiology, and an understanding of how such results may affect patient care.

A systematic review of cost-effectiveness analysis of screening interventions for assessing the risk of venous thromboembolism in women considering combined oral contraceptives

Use of combined oral contraceptives (COCs) by women increases the risk of venous thromboembolism (VTE), which can have a major impact on an individuals' quality of life. VTE is also associated with an increase in healthcare costs. Our aim was to systematically review cost-effectiveness analyses (CEAs) considering any screening for risk of VTE in women using COCs. The quality of reporting in each study was assessed, a summary of results was prepared, and the key drivers of cost effectiveness in each of the eligible CEAs were identified. A search strategy using MeSH terms was performed in MEDLINE, Embase, the Centre for Review and Dissemination (CRD) database including the Economic Evaluation Database from the UK National Health Service, and Cochrane reviews. Two reviewers independently screened and determined the final articles, and a third reviewer resolved any discrepancies. Consolidated Health Economic Evaluation Reporting Standards was used to assess the quality of reporting in terms of perspective, effectiveness measures, model structure, cost, time-horizon and discounting. Four publications (three from Europe, one from the United States) were eligible for inclusion in the review. According to current criteria, relevant elements were sometimes not captured and the sources of epidemiological and effectiveness data used in the CEAs were of limited quality. The studies varied in terms of type of costs assessed, country settings, model assumptions and uncertainty around input parameters. Key drivers of CEAs were sensitivity and specificity of the test, incidence rate of VTE, relative risk of prophylaxis, and costs of the test. The reviewed studies were too dissimilar to draw a firm conclusion on cost-effectiveness analysis about universal and selective screening in high-risk groups. The new emerging diagnostic tools for identifying women at risk of developing VTE, that are more predictive and less costly, highlight the need for more studies that apply the latest evidence and utilize robust methods for cost-effectiveness analysis. This information is required to improve decision making for this pertinent issue within personalized medicine.

Thromboembolism peaking 3 months after starting testosterone therapy: testosterone–thrombophilia interactions

We assessed time of thrombotic events (venous thromboembolism (VTE)) after starting testosterone therapy (TT) in 21 men who sustained 23 VTE. The density of thrombotic events was greatest at 3 months after starting TT, with a rapid decline in events by 10 months. The 21 cases with VTE on TT differed from 110 patient controls with unprovoked VTE, not taking TT (VTE-no TT) for Factor V Leiden heterozygosity (FVL) (33 per cent vs 13 per cent, P=0.037), for high lipoprotein (a) (Lp(a)) (55 per cent vs 17 per cent, P=0.012), and for the lupus anticoagulant (33 per cent vs 4 per cent, P=0.003). These differences between cases and VTE-no TT controls were independent of age and gender. TT can interact with underlying thrombophilia–hypofibrinolysis promoting VTE. We suggest that TT should not be started in subjects with known thrombophilia. Coagulation screening, particularly for the FVL , Lp(a), and the lupus anticoagulant should be considered before starting TT, to identify men at high VTE risk who have an adverse risk/benefit ratio for TT.

Obstetric complications and pregnancy-related venous thromboembolism: The effect of low-molecular-weight heparin on their prevention in carriers of factor V Leiden or prothrombin G20210A mutation

Whether the administration of low-molecular-weight heparin (LMWH) during pregnancy is effective in preventing obstetric complications and pregnancy-related venous thromboembolism (VTE) in women who are carriers of factor V Leiden (FVL) and/or prothrombin variant G20210A (PTm) is controversial. This observational study investigated the possible efficacy of pharmacological treatment with LMWH ± aspirin (ASA) in pregnancy outcomes in 1,011 pregnancies of 416 women with thrombophilia (FVL and/or PTm). Most patients were chosen on the basis of previous obstetrical complications (36%), or because of familial or personal history of venous/arterial thromboembolism (28% and 18%, respectively); 74 patients (18%) were incidentally identified. The outcome was evaluated according to the type of treatment and of the period of pregnancy when the treatment was started. After adjustment for observation before and after diagnosis of thrombophilia, previous miscarriages and VTE, parity, age and centre, we observed that LMWH had a protective effect on miscarriages (odds ratio [OR] 0.52, 95% confidence interval [CI] 0.29–0.94) and VTE (OR 0.05, 95% CI 0.01–0.21). ASA appeared to have no effect on the prevention of obstetric complications and VTE. A nested analysis performed in 116 women with two or more obstetric complications confirmed that the highest number of live births was recorded in the group under LMWH prophylaxis (OR 0.19, 95% CI 0.05–0.75). These results suggest that LMWH prophylaxis reduces the risk of obstetric complications in carriers of FVL and/or PTm, particularly in those with previous obstetric events. Furthermore, LMWH prophylaxis reduces the risk of pregnancy-related VTE.

Economic Evaluations of Thrombophilia Screening Prior to Prescribing Combined Oral Contraceptives: A Systematic and Critical Review

BACKGROUND

Combined oral contraceptives (COCs) increase the risk of venous thromboembolism (VTE), particularly among women with inherited clotting disorders. The World Health Organization classifies combined hormonal contraception as an "unacceptable health risk" for women with thrombogenic mutations but advises against universal thrombophilia screening before prescribing COCs given the low prevalence of thrombophilia and high screening costs.

OBJECTIVE

Through the lens of lifetime costs and benefits, this paper systematically and critically reviews all published economic evaluations of thrombophilia screening prior to prescribing COCs.

METHODS

We searched relevant databases for economic evaluations of thrombophilia screening before prescribing COCs. After extracting the key study characteristics and economic variables, we evaluated each article using the Quality of Health Economic Studies (QHES) and the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) instruments.

RESULTS

Seven economic evaluations of thrombophilia screening before prescribing COCs met our inclusion criteria. Only the two economic evaluations focusing exclusively on selective screening exceeded the 75-point threshold for high-quality economic studies based on the QHES instrument, whereas only one of these exceeded the 85% CHEERS threshold. Only three of the seven economic evaluations performed sensitivity analysis on key parameters. Most studies underestimated the benefits of thrombophilia screening by comparing one-time costs of genetic screening against benefits per person-year, thus implicitly assuming a 1-year duration of COC use, neglecting the long-term implications of VTE and/or neglecting the lifetime benefits of awareness of inherited thrombophilia.

CONCLUSION

Our review highlights the lack of methodologically rigorous economic evaluations of universal thrombophilia screening before prescribing COCs.

Thrombophilia Screening: Universal, Selected, or Neither?

The utility of thrombophilia testing in clinical practice is still a matter of debate because studies have not shown a benefit in the reduction of recurrent venous thromboembolism (VTE) risk in patients with thrombosis, despite the clearly higher VTE risk for first thrombosis. Screening for thrombophilia is indicated in selected patients. Particularly in selected young patients, especially women of childbearing age, the knowledge of the genetic thrombophilic defect may help in specific situations to decrease the risk of VTE events. Avoidance of modifiable risk factors and/or prophylactic thromboembolic procedures may be evaluated in selected patients. A comprehensive workup including personal and familial history, clinical examination, and laboratory test results including hereditary thrombophilia remains helpful in assessing the cumulative risk and the management of this group of selected patients.

Guidance for the evaluation and treatment of hereditary and acquired thrombophilia

Thrombophilias are hereditary and/or acquired conditions that predispose patients to thrombosis. Testing for thrombophilia is commonly performed in patients with venous thrombosis and their relatives; however such testing usually does not provide information that impacts management and may result in harm. This manuscript, initiated by the Anticoagulation Forum, provides clinical guidance for thrombophilia testing in five clinical situations: following 1) provoked venous thromboembolism, 2) unprovoked venous thromboembolism; 3) in relatives of patients with thrombosis, 4) in female relatives of patients with thrombosis considering estrogen use; and 5) in female relatives of patients with thrombosis who are considering pregnancy. Additionally, guidance is provided regarding the timing of thrombophilia testing. The role of thrombophilia testing in arterial thrombosis and for evaluation of recurrent pregnancy loss is not addressed. Statements are based on existing guidelines and consensus expert opinion where guidelines are lacking. We recommend that thrombophilia testing not be performed in most situations. When performed, it should be used in a highly selective manner, and only in circumstances where the information obtained will influence a decision important to the patient, and outweigh the potential risks of testing. Testing should not be performed during acute thrombosis or during the initial (3-month) period of anticoagulation.

Update on the Cardiovascular Risks of Hormone Replacement Therapy

Systematic reviews of randomized, controlled trials have shown that use of hormone replacement therapy in women increases the risk of total cardiovascular disease (venous thromboembolism, stroke and coronary heart disease; there may also be an increased risk of peripheral arterial disease). The relative increase in risk is similar to that for use of combined oral contraceptives, but the absolute increase in risk is higher owing to the higher age of hormone replacement therapy users. The increased risk appears confined to current users, increases with age and obesity, and may differ with type of preparation. Transdermal hormone replacement therapy may carry a lower risk of venous thromboembolism compared with oral hormone replacement therapy. The mechanism for the increased risk is probably activated blood coagulation. The risk of venous thromboembolism is higher in women with thrombophilias; however, the value of screening for thrombophilias is not established. Further research is required to establish the risks of cardiovascular (and other) diseases in different groups of women for different types of hormone replacement therapy, including an individual participant meta-analysis of reported randomized, controlled trials.

Selective Thrombophilia Screening in Young Patients with Retinal Artery Occlusion

Purpose: To investigate the prevalence of various thrombophilic disorders among young patients with retinal artery occlusion (RAO). Procedures: We retrospectively reviewed thrombophilia screening data of young patients ≤60 years of age with RAO and healthy controls matched for gender and age. Results: Thrombophilia screening data of 25 young patients and 62 healthy controls were analyzed. Mean patient age by the time of the RAO was 43.3 ± 10.8 years. Overall, thrombophilic defects were found to be present in 17 patients (68%) compared with 11 of 62 controls (17.7%; p < 0.0001). Multivariate logistic regression analysis confirmed a statistically significant association between the development of RAO and increased levels of lipoprotein(a) (odds ratio: 9.48; p = 0.001) and factor VIII (odds ratio: 6.41; p = 0.024). There was a strong association between the presence of thrombophilic disorders and a personal or family history of thromboembolism (p = 0.01). Conclusions: Our results indicate that screening for thrombophilic disorders among selected young patients with RAO yields positive results in a high percentage of cases.

Hospitalization for pulmonary embolism associated with antecedent testosterone or estrogen therapy in patients found to have familial and acquired thrombophilia

BACKGROUND

In patients hospitalized over a 4 year period for pulmonary embolism (PE), we assessed relationships of testosterone (TT) and estrogen therapy (ET) anteceding PE in patients found to have familial-acquired thrombophilia.

METHODS

From 2011 through 2014, 347 patients were hospitalized in Cincinnati Mercy Hospitals with PE. Retrospective chart review was used to identify patients receiving TT or ET before PE; coagulation studies were done prospectively if necessary.

RESULTS

Preceding hospitalization for PE, 8 of 154 men (5 %) used TT, and 24 of 193 women (12 %) used ET. The median number of months from the initiation of TT or ET to development of PE was 7 months in men and 18 months in women. Of the 6 men having coagulation measures, all had ≥ 1 thrombophilia, and of the 18 women having measures of coagulation, 16 had ≥ 1 thrombophilia. The sensitivity of a previous history of thrombosis to predict PE was low, 25 % (2/8 men), 4 % (1/24 women).

CONCLUSIONS

Of 154 men hospitalized for PE, 8 (5 %) used TT, and of 193 women, 24 (12 %) used ET. Our data suggests that PE is an important complication of TT in men and ET in women, in part reflecting an interaction between familial and acquired thrombophilia and exogenous hormone use.

Thrombophilia in 67 Patients With Thrombotic Events After Starting Testosterone Therapy

We compared thrombophilia in 67 cases (59 men and 8 women) with thrombotic events after starting testosterone therapy (TT) versus 111 patient controls having unprovoked venous thrombotic events without TT. In the 67 patients, thrombosis (47 deep venous thrombosis-pulmonary embolism, 16 osteonecrosis, and 4 ocular thrombosis) occurred 6 months (median) after starting TT. Cases differed from controls for factor V Leiden heterozygosity (16 of the 67 [24%] vs 13 [12%] of the 111, P = .038) and for lupus anticoagulant (9 [14%] of the 64 vs 4 [4%] of the 106, P = .019). After a first thrombotic event and continuing TT, 11 cases had a second thrombotic event, despite adequate anticoagulation, 6 of whom, still anticoagulated, had a third thrombosis. Screening for thrombophilia before starting TT should identify men and women at high risk for thrombotic events with an adverse risk-benefit ratio for TT. When TT is given to patients with familial and acquired thrombophilia, thrombosis may occur and recur in thrombophilic men despite anticoagulation.

Risk factors for venous thromboembolism in women under combined oral contraceptive. The PILl Genetic RIsk Monitoring (PILGRIM) Study

Identifying women at risk of venous thromboembolism (VTE) is a major public health issue. The objective of this study was to identify environmental and genetic determinants of VTE risk in a large sample of women under combined oral contraceptives (COC). A total of 968 women who had had one event of VTE during COC use were compared to 874 women under COC but with no personal history of VTE. Clinical data were collected and a systematic thrombophilia screening was performed together with ABO blood group assessment. After adjusting for age, family history, and type and duration of COC use, main environmental determinants of VTE were smoking (odds ratio [OR] =1.65, 95% confidence interval [1.30-2.10]) and a body mass index higher than 35 kg.m⁻² (OR=3.46 [1.81-7.03]). In addition, severe inherited thrombophilia (OR=2.13 [1.32-3.51]) and non-O blood groups (OR=1.98 [1.57-2.49]) were strong genetic risk factors for VTE. Family history poorly predicted thrombophilia as its prevalence was similar in patients with or without first degree family history of VTE (29.3% vs 23.9%, p=0.09). In conclusion, this study confirms the influence of smoking and obesity and shows for the first time the impact of ABO blood group on the risk of VTE in women under COC. It also confirms the inaccuracy of the family history of VTE to detect inherited thrombophilia.

Oral contraception

Oral contraception (OC) remains a popular noninvasive, readily reversible approach for pregnancy prevention and, largely off label, for control of acne, hirsutism, dysmenorrhea, irregular menstruation, menorrhagia, and other menstrual-related symptoms. Many OC formulations exist, with generics offering lower cost and comparable efficacy. Certain medical conditions, including hypertension, migraine, breast cancer, and risk of venous thromboembolism (VTE), present contraindications. Blood pressure measurement is the only physical examination or testing needed before prescription. Although no OC is clearly superior to others, OCs containing the second-generation progestin levonorgestrel have been associated with lower VTE risk than those containing other progestins.

Testosterone, thrombophilia, thrombosis

We screened previously undiagnosed thrombophilia (V Leiden-prothrombin mutations, Factors VIII and XI, homocysteine, and antiphospholipid antibody [APL] syndrome) in 15 men and 2 women with venous thromboembolism (VTE) or osteonecrosis 7 months (median) after starting testosterone therapy (TT), gel (30-50 mg/d), intramuscular (100-400 mg/wk), or human chorionic gonadotropin (HCG) (6000 IU/wk). Thrombophilia was studied in 2 healthy control groups without thrombosis (97 normal controls, 31 subjects on TT) and in a third control group (n = 22) with VTE, not on TT. Of the 17 cases, 76% had ≥1 thrombophilia vs 19% of 97 normal controls (P < 0.0001), vs 29% of 31 TT controls (P = 0.002). Cases differed from normal controls by Factor V Leiden (12% vs 0%, P = 0.021), by high Factor VIII (>150%) (24% vs 7%, P = 0.058), by high homocysteine (29% vs 5%, P = 0.007), and from both normal and TT controls for APL syndrome (18% vs 2%, P = 0.023, vs 0%, P = 0.04). Despite adequate anticoagulation with TT continued after the first deep venous thrombosis-pulmonary embolus (DVT-PE), 1 man sustained 3 DVT-PEs 5, 8, and 11 months later and a second man had 2 DVT-PEs 1 and 2 months later. Of the 10 cases with serum T measured on TT, 6 (60%) had supranormal T (>800 ng/dL) and of 9 with estradiol measured on TT, 7 (78%) had supranormal levels (>42.6 pg/mL). TT interacts with thrombophilia leading to thrombosis. TT continuation in thrombophilic men is contraindicated because of recurrent thrombi despite anticoagulation. Screening for thrombophilia before starting TT should identify subjects at high risk for VTE with an adverse the risk to benefit ratio for TT.

Multilocus genetic risk scores for venous thromboembolism risk assessment

BACKGROUND

Genetics plays an important role in venous thromboembolism (VTE). Factor V Leiden (FVL or rs6025) and prothrombin gene G20210A (PT or rs1799963) are the genetic variants currently tested for VTE risk assessment. We hypothesized that primary VTE risk assessment can be improved by using genetic risk scores with more genetic markers than just FVL-rs6025 and prothrombin gene PT-rs1799963. To this end, we have designed a new genetic risk score called Thrombo inCode (TiC).

METHODS AND RESULTS

TiC was evaluated in terms of discrimination (Δ of the area under the receiver operating characteristic curve) and reclassification (integrated discrimination improvement and net reclassification improvement). This evaluation was performed using 2 age- and sex-matched case-control populations: SANTPAU (248 cases, 249 controls) and the Marseille Thrombosis Association study (MARTHA; 477 cases, 477 controls). TiC was compared with other literature-based genetic risk scores. TiC including F5 rs6025/rs118203906/rs118203905, F2 rs1799963, F12 rs1801020, F13 rs5985, SERPINC1 rs121909548, and SERPINA10 rs2232698 plus the A1 blood group (rs8176719, rs7853989, rs8176743, rs8176750) improved the area under the curve compared with a model based only on F5-rs6025 and F2-rs1799963 in SANTPAU (0.677 versus 0.575, P<0.001) and MARTHA (0.605 versus 0.576, P=0.008). TiC showed good integrated discrimination improvement of 5.49 (P<0.001) for SANTPAU and 0.96 (P=0.045) for MARTHA. Among the genetic risk scores evaluated, the proportion of VTE risk variance explained by TiC was the highest.

CONCLUSIONS

We conclude that TiC greatly improves prediction of VTE risk compared with other genetic risk scores. TiC should improve prevention, diagnosis, and treatment of VTE.

Testosterone therapy, thrombosis, thrombophilia, cardiovascular events

There are similar time intervals between starting testosterone therapy (TT) and development of thrombotic (~4.5 months) or cardiovascular (CVD) events (~3 months) which may, speculatively, reflect a shared pathophysiology. We have described thrombotic events 5 months (median) after starting TT in 38 men and 4 women, including 27 with deep venous thrombosis-pulmonary embolism, 12 with osteonecrosis, 1 with central retinal vein thrombosis, 1 with amaurosis fugax, and 1 with spinal cord infarction. In 8 men whose TT was continued, second thrombotic events occurred despite adequate anticoagulation with Coumadin in 8 men, 3 of whom had a third thrombotic event. Of these 42 cases, 40 had measures of thrombophilia-hypofibrinolysis, and 39 were found to have previously undiagnosed thrombophilia-hypofibrinolysis. Before beginning TT, especially in men with previous history of thrombotic events, we suggest that, at a minimum, measurements be made for the Factor V Leiden and Prothrombin mutations, Factors VIII and XI, and homocysteine, to identify men who should not receive TT. We need prospective data focused on whether there should be pre-TT screening based on history of previous venous thromboembolism or for all subjects for major gene thrombophilias. To better resolve questions about TT and all cause and cardiovascular morbidity and mortality and thrombosis, a long term, prospective, randomized, blinded study following the example of the Women's Health Initiative is needed. While we wait for prospective placebo-controlled TT outcome data, TT should be restricted to men with well-defined androgen deficiency syndromes.

Prophylaxis for venous thromboembolic disease in pregnancy and the early postnatal period

BACKGROUND

Venous thromboembolism (VTE), although rare, is a major cause of maternal mortality and morbidity, and methods of prophylaxis are therefore often used for women considered to be at risk. This may include women who have given birth by caesarean section, those with a personal or family history of VTE and women with inherited or acquired thrombophilias (conditions that predispose people to thrombosis). Many methods of prophylaxis carry risks of adverse effects, and as the risk of VTE is often low, it is possible that the benefits of thromboprophylaxis may be outweighed by harms. Guidelines for clinical practice have been based on expert opinion rather than high-quality evidence from randomised trials.

OBJECTIVES

To assess the effects of thromboprophylaxis in women who are pregnant or have recently given birth and are at increased risk of VTE on the incidence of VTE and adverse effects of treatment.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (27 November 2013). 

SELECTION CRITERIA

Randomised trials comparing one method of thromboprophylaxis with placebo or no treatment, and randomised trials comparing two (or more) methods of thromboprophylaxis.

DATA COLLECTION AND ANALYSIS

At least two review authors assessed trial eligibility and quality and extracted the data.

MAIN RESULTS

Nineteen trials, at an overall moderate risk of bias, met the inclusion criteria for the review. Only 16 trials, involving 2592 women, assessing a range of methods of thromboprophylaxis, contributed data to the review. Six trials compared methods of antenatal prophylaxis: heparin versus no treatment/placebo (two trials), and low molecular weight heparin (LMWH) versus unfractionated heparin (UFH) (four trials). Nine trials assessed prophylaxis after caesarean section: four compared heparin with placebo; three compared LMWH with UFH; one compared hydroxyethyl starch (HES) with UFH; and one compared five-day versus 10-day LMWH. One study examined prophylaxis with UFH in the postnatal period (including following vaginal births).For antenatal prophylaxis, none of the included trials reported on maternal mortality, and no differences were detected for the other primary outcomes of symptomatic thromboembolic events, symptomatic pulmonary embolism (PE) and symptomatic deep venous thrombosis (DVT) when LMWH or UFH was compared with no treatment/placebo or when LMWH was compared with UFH. The risk ratios (RR) for symptomatic thromboembolic events were: antenatal LMWH/UFH versus no heparin, RR 0.33; 95% confidence interval (CI) 0.04 to 2.99 (two trials, 56 women); and antenatal LMWH versus UFH, RR 0.47; 95% CI 0.09 to 2.49 (four trials, 404 women). No differences were shown when antenatal LMWH or UFH was compared with no treatment/placebo for any secondary outcomes. Antenatal LMWH was associated with fewer adverse effects sufficient to stop treatment (RR 0.07; 95% CI 0.01 to 0.54; two trials, 226 women), and fewer fetal losses (RR 0.47; 95% CI 0.23 to 0.95; three trials, 343 women) when compared with UFH. In two trials, antenatal LMWH compared with UFH was associated with fewer bleeding episodes (defined in one trial of 121 women as bruises > 1 inch (RR 0.18, 95% CI 0.09 to 0.36); and in one trial of 105 women as injection site haematomas of ≥ 2 cm, bleeding during delivery or other bleeding (RR 0.28; 95% CI 0.15 to 0.53)), however in a further trial of 117 women no difference between groups was shown for bleeding at delivery. The results for these secondary outcomes should be interpreted with caution, being derived from small trials that were not of high methodological quality.For post-caesarean/postnatal prophylaxis, only one trial comparing five-day versus 10-day LMWH after caesarean section reported on maternal mortality, observing no deaths. No differences were seen across any of the comparisons for the other primary outcomes (symptomatic thromboembolic events, symptomatic PE and symptomatic DVT). The RRs for symptomatic thromboembolic events were: post-caesarean LMWH/UFH versus no heparin, RR 1.30; 95% CI 0.39 to 4.27 (four trials, 840 women); post-caesarean LMWH versus UFH, RR 0.33; 95% CI 0.01 to 7.99 (three trials, 217 women); post-caesarean five-day versus 10-day LMWH, RR 0.36; 95% CI 0.01 to 8.78 (one trial, 646 women); postnatal UFH versus no heparin, RR 0.16; 95% CI 0.02 to 1.36 (one trial, 210 women). For prophylaxis after caesarean section, in one trial (of 580 women), women receiving UFH and physiotherapy were more likely to have bleeding complications ('complications hémorragiques') than women receiving physiotherapy alone (RR 5.03; 95% CI 2.49 to 10.18). In two additional trials, that compared LMWH with placebo, no difference between groups in bleeding episodes (major bleeding; major bruising; bleeding/bruising reported at discharge) were detected. No other differences in secondary outcomes were shown when LMWH was compared with UFH post-caesarean, nor when post-caesarean HES was compared with UFH, post-caesarean five-day LMWH was compared with 10-day LMWH, or when UFH was compared to no heparin postnatally.

AUTHORS' CONCLUSIONS

There is insufficient evidence on which to base recommendations for thromboprophylaxis during pregnancy and the early postnatal period, with the small number of differences detected in this review being largely derived from trials that were not of high methodological quality. Large scale, high-quality randomised trials of currently used interventions are warranted.

Genetic screening for the predisposition to venous thromboembolism: a cost-utility analysis of clinical practice in the Italian health care system

OBJECTIVES

In the Italian health care system, genetic tests for factor V Leiden and factor II are routinely prescribed to assess the predisposition to venous thromboembolism (VTE) of women who request oral contraception. With specific reference to two subpopulations of women already at risk (i.e., familial history or previous event of VTE), the study aimed to assess whether current screening practices in Italy are cost-effective.

METHODS

Two decisional models accrued costs and quality-adjusted life-years (QALY) annually from the perspective of the National Health Service. The two models were derived from a decision analysis exercise concerning testing practices and consequent prescribing behavior for oral contraception conducted with 250 Italian gynecologists. Health care costs were compiled on the basis of 10-year hospital discharge records and the activities of a thrombosis center. Whenever possible, input data were based on the Italian context; otherwise, the data were taken from the international literature.

RESULTS

Current testing practices on women with a familial history of VTE generate an incremental cost-effectiveness ratio of €72,412/QALY, which is well above the acceptable threshold of cost-effectiveness of €40,000 to €50,000/QALY. In the case of women with a previous event of VTE, the most frequently used testing strategy is cost-ineffective and leads to an overall loss of QALY.

CONCLUSIONS

This study represents the first attempt to conduct a cost-utility analysis of genetic screening practices for the predisposition to VTE in the Italian setting. The results indicate that there is an urgent need to better monitor the indications for which tests for factor V Leiden and factor II are prescribed.

Testing for inherited thrombophilia and consequences for antithrombotic prophylaxis in patients with venous thromboembolism and their relatives. A review of the Guidelines from Scientific Societies and Working Groups

The clinical penetrance of venous thromboembolism (VTE) susceptibility genes is variable, being lower in heterozygous carriers of factor V Leiden and prothrombin 20210A (mild thrombophilia), and higher in the rare carriers of deficiencies of antithrombin, protein C or S, and those with multiple or homozygous abnormalities (high-risk thrombophilia). The absolute risk of VTE is low, and the utility of laboratory investigation for inherited thrombophilia in patients with VTE and their asymptomatic relatives has been largely debated, leading to the production of several Guidelines from Scientific Societies and Working Groups. The risk for VTE largely depends on the family history of VTE. Therefore, indiscriminate search for carriers is of no utility, and targeted screening is potentially more fruitful. In patients with VTE inherited thrombophilia is not scored as a determinant of recurrence, playing a minor role in the decision of prolonging anticoagulation; indeed, a few guidelines consider testing worthwhile to identify carriers of high-risk thrombophilia, particularly those with a family history of VTE. The identification of the asymptomatic carrier relatives of the probands with VTE and thrombophilia could reduce cases of provoked VTE, offering them primary antithrombotic prophylaxis during risk situations. In most guidelines, this is considered justified only for relatives of probands with a deficiency of natural anticoagulants or multiple abnormalities. Counselling the asymptomatic female relatives of individuals with VTE and/or thrombophilia before pregnancy or the prescription of hormonal treatments should be administered with consideration of the risk driven by the type of thrombophilia and the family history of VTE.

Flow-simulated thrombin generation profiles as a predictor of thrombotic risk among pre-menopausal women

A large number of individuals are at risk for deep venous thrombosis (DVT) due to alterations in multiple coagulation factors and inhibitors secondary to malignancy, drug interactions, or other general medical conditions. Traditional metrics of haemostasis such as prothrombin time, partial thromboplastin time, and bleeding time, generally estimate anticoagulation status and bleeding risk rather than thrombosis risk. The objective of this study was to correlate a novel, systems-based metric of clotting potential to risk of DVT from a database derived from the Leiden Thrombophilia Study (LETS). We utilised a computational model of blood coagulation, which addresses the interplay between biochemical factors, blood flow, and physiologic surface initiation of coagulation, to calculate an individualised, systems-based metric of clotting potential, termed the flow-simulated thrombin generation (FSTG), for 210 pre-menopausal women in LETS. Both DVT and oral contraceptive (OC) use were associated with higher values of FSTG. We demonstrated a nearly three-fold increased risk of DVT for each standard deviation increase above the mean in FSTG determined under venous flow conditions, which remained highly predictive after adjustment for age and OC status (adjusted odds ratio 2.66; 95% confidence interval 1.69-4.19; p<0.0001). In conclusion, a systems-based screening approach that integrates biochemical factors and flow haemodynamics identifies small subgroups of patients at risk of thrombosis that may benefit from oral anticoagulants.