Genetic Risk Factors in Venous Thromboembolism

The association of the prothrombin A19911G single-nucleotide polymorphism and the risk of venous thromboembolism: A systematic review and meta-analysis

BACKGROUND

The study employed meta-analysis to provide a comprehensive synthesis of evidence regarding the association between the prothrombin A19911G polymorphism and the risk of venous thromboembolism (VTE).

METHOD

The databases were searched to identify studies investigating the association between the prothrombin A19911G polymorphism and the risk of VTE. Meta-analysis was conducted using Stata 14.0 software.

RESULTS

A total of five literature studies were included, involving 14,001 participants. Meta-analysis demonstrated that prothrombin A19911G polymorphism increased the risk of VTE (G vs A: OR = 1.17, 95% CI = 1.11-1.22, p < .00001; GG + AG vs AA: OR = 1.22, 95% CI = 1.13-1.31, p < .00001; GG vs AG + AA: OR = 1.23, 95% CI = 1.14-1.33, p < .00001; AG vs AA: OR = 1.15, 95% CI = 1.06-1.25, p = .0006; GG vs AA: OR = 1.34, 95% CI = 1.22-1.48, p < .00001).

CONCLUSION

The polymorphism of prothrombin A19911G enhances the susceptibility to VTE.

Impact of Inherited Thrombophilia in Women with Obstetric Antiphospholipid Syndrome: A Single-Center Study and Literature Review

Inherited thrombophilia (IT) has been implicated as a potential causal factor of adverse pregnancy outcomes (APOs), including recurrent miscarriage with and without the presence of antiphospholipid syndrome (APS). The aim of this study was to assess the prevalence and impact of IT on fetal-maternal outcomes and thrombotic risk in women within the spectrum of obstetric APS. Three hundred and twenty-eight women with APS-related obstetric morbidity ever pregnant were included. Of these, 74 met the APS classification criteria, 169 were non-criteria (NC)-APS, and 85 were seronegative (SN)-APS. Patients with other autoimmune diseases were excluded. APOs included early pregnancy loss, fetal death, preeclampsia, abruptio placentae, and preterm birth. Successful pregnancy was defined as the achievement of a live newborn. A literature search was also performed. The mean age of the overall group was 33.9 ± 5.3 years, and the patients were followed up for 35 (11-79) months. During the study period, there were 1332 pregnancies. Nearly 14% of the patients had an associated IT. IT patients more frequently received the standard-of-care (SoC) therapy. The presence of IT was not associated with worse maternal-fetal outcomes in patients treated with SoC treatment. Overall, IT patients had a lower frequency of newborns without treatment, especially those without definite APS. In addition, IT did not increase the risk of thrombosis during pregnancy or the postpartum period. A detailed analysis of the literature review identified only four publications related to our study and did not show conclusive evidence of the impact of IT on patients with obstetric APS. The group of women with APS-related obstetric morbidity and IT who did not receive treatment, especially those without definite APS, had a worse prognosis in terms of a live birth. However, with SoC therapy, the prognosis is similar in those patients without IT. The association of IT with APS does not seem to predispose to the development of thrombosis during pregnancy and/or the postpartum period.

The relevance of prothrombotic genetic variants in women who experienced pregnancy loss or embryo implantation failure: A retrospective analysis of 1922 cases

OBJECTIVE

The aim of our study was that to assess the allelic and genotype frequencies of nine prothrombotic gene variants in patients with a history of pregnancy loss and recurrent pregnancy loss (RPL). Women who underwent assisted reproductive technology (ART) with ongoing pregnancy and those with recurrent implantation failure (RIF) were also included.

METHODS

Nine prothrombotic gene variants were evaluated: factor V Leiden (FVL), factor V, H1299R variant (FVR2), factor II (FII) G20210A, methylene-tetrahydrofolate reductase (MTHFR) C677T and A1298C, beta-fibrinogen -455G>A, factor XIII (FXIII) V34L, human platelet antigen-1 (HPA-1) L33P variants, and plasminogen activator inhibitor-1 (PAI-1) 4G/5G. The following study groups were assessed: (1) women who experienced one (n = 334) or two (n = 264) episodes of pregnancy loss; (2) 468 women who experienced RPL; (3) 214 women who underwent ART followed by ongoing pregnancies; and (4) 282 women who experienced RIF after ART, that is, three or more consecutive implantation failures following high-quality embryo transfers to the uterus with an appropriate endometrium. As control group, 430 subjects from the general population were enrolled.

RESULTS

FVL, the -455G>A variant of beta-fibrinogen, and PAI-1 4G were associated with a higher risk of developing RPL compared with the general population. Furthermore, FVL, FVR2, FII G20210A and MTHFR C677T conferred a significantly higher risk of RIF in women who performed ART compared with the general population. No statistical differences between the general population and other study groups were observed.

CONCLUSIONS

Specific prothrombotic genetic variants are more frequently expressed in women with RPL and RIF, supporting their role in the development of polimicrothrombosis and impairing the invasion during embryo implantation.

Evaluation of prothrombotic risk of two PROC hotspot mutations (Arg189Trp and Lys193del) in Chinese population: a retrospective study

BACKGROUND

R189W and K193del of protein C (PC) were hotspot mutations in Chinese population with venous thromboembolism (VTE), but almost two-thirds of patients with above mutations coexisting with other genetically or aquiredly prothrombotic risk factors. The aim of this study is to clarify the independent contributions of R189W or K193del to VTE risk.

METHODS

490 unrelated patients with a personal history of VTE and 410 healthy participants were enrolled in this study. Data of their demographics, family history, genetic and acquired thrombosis risk factors were collected and statistically analyzed.

RESULTS

PC R189W and K193del were identified in 3/410 (0.7%) and 7/410 (1.7%) healthy controls, and in 27/490 (5.5%) and 43/490 (8.8%) patients with VTE, respectively. Notably, about 70% of these mutant carriers combined with other genetic or acquired thrombophilic factors. After adjustment for age, gender, other inherited and acquired risk factors, we demonstrated that R189W and K193del were associated with 5.781-fold and 4.365-fold increased risk of VTE, respectively, which were significantly lower than the prothrombotic risk of anticoagulant deficiencies induced from rare mutations. Independent R189W or K193del mutation was not associated with earlier first-onset age as well as higher recurrent rate of VTE. However, combination of other genetic or acquired thrombophilic factors had supra-additive effects on those consequences. The more additional risk factors the patients had, the younger first-onset ages and higher risk of recurrence would be.

CONCLUSIONS

As the most frequent mutations for PC deficiency in Chinese population, both R189W and K193del mutations had limited independent contributions to VTE development compared with other rare mutations in PROC gene, but may act in concert with other genetic defects or acquired thrombotic risk factors to produce the final severe phenotype.

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.

Genome-wide association analyses identified novel susceptibility loci for pulmonary embolism among Han Chinese population

BACKGROUND

A large proportion of pulmonary embolism (PE) heritability remains unexplained, particularly among the East Asian (EAS) population. Our study aims to expand the genetic architecture of PE and reveal more genetic determinants in Han Chinese.

METHODS

We conducted the first genome-wide association study (GWAS) of PE in Han Chinese, then performed the GWAS meta-analysis based on the discovery and replication stages. To validate the effect of the risk allele, qPCR and Western blotting experiments were used to investigate possible changes in gene expression. Mendelian randomization (MR) analysis was employed to implicate pathogenic mechanisms, and a polygenic risk score (PRS) for PE risk prediction was generated.

RESULTS

After meta-analysis of the discovery dataset (622 cases, 8853 controls) and replication dataset (646 cases, 8810 controls), GWAS identified 3 independent loci associated with PE, including the reported loci FGG rs2066865 (p-value = 3.81 × 10^-14), ABO rs582094 (p-value = 1.16 × 10^-10) and newly reported locus FABP2 rs1799883 (p-value = 7.59 × 10^-17). Previously reported 10 variants were successfully replicated in our cohort. Functional experiments confirmed that FABP2-A163G(rs1799883) promoted the transcription and protein expression of FABP2. Meanwhile, MR analysis revealed that high LDL-C and TC levels were associated with an increased risk of PE. Individuals with the top 10% of PRS had over a fivefold increased risk for PE compared to the general population.

CONCLUSIONS

We identified FABP2, related to the transport of long-chain fatty acids, contributing to the risk of PE and provided more evidence for the essential role of metabolic pathways in PE development.

A review of venous thromboembolism risk assessment models for different patient populations: What we know and don't!

Venous thromboembolism (VTE) is a common cause of morbidity and mortality in hospitalized patients. Globally, it is also the third leading vascular disease, after myocardial infarction and stroke. The incidence of VTE is reportedly higher in Western countries than in Asian countries. However, recent reports suggest an increasing incidence of VTE in Asian countries, including India. Since VTE is largely a preventable disease, early identification of risk factors can lead to disease prevention or the adoption of appropriate prophylactic measures. To this end, several VTE risk assessment models (RAMs) have been developed and validated for different populations who are at risk of developing VTE, such as hospitalized patients with medical illness/surgical indication, patients with cancer, and pregnant women. Evidence indicates that the systematic use of RAMs improves prophylaxis rates and lowers the burden of VTE. Given the increasing burden of VTE in the Indian population and poor prophylaxis rates, the implementation of systematic RAMs in routine clinical practice might ameliorate the disease burden in the country. We have assessed the evidence-based utilities of available RAMs and have delineated the most common and suitable RAMs for different populations including coronavirus disease 2019 affected patients. This review depicts the current status of implementation and validation of RAMs in the Indian scenario. It also highlights the need for additional validation studies, improved awareness, and implementation of RAMs in clinical practice for lowering the burden of VTE.

Genetic Predisposition of Both Waist Circumference and Hip Circumference Increased the Risk of Venous Thromboembolism

BACKGROUND

 Obesity, especially abdominal obesity, is an independent indicator of increased cardiovascular risk. Observational studies have shown an observational association between obesity and venous thromboembolism (VTE). As a type of VTE, pulmonary embolism (PE) is also associated with obesity. However, it is unclear whether the observed associations are causal or caused by confounding bias or reverse causality.

METHODS

 We performed a two-sample test by obtaining the exposure dataset of waist circumference (WC) and hip circumference (HC) from the Neale Laboratory Consortium's genome-wide association study summary data and the summary-level outcome data of VTE and PE from FinnGen Biobank of European ancestry to determine the causal effect of WC and HC on VTE and PE.

RESULTS

 All three Mendelian randomization methods displayed a positive association between WC/HC and VTE/PE. WC and HC were positively associated with VTE (odds ratio [OR] = 1.803 per 1 standard deviation [SD] increase in WC, 95% confidence interval [CI] = 1.393-2.333; p < 0.001; OR = 1.479 per 1 SD increase in HC, 95% CI = 1.219-1.796; p < 0.001, respectively). Furthermore, we found a causal association between genetically predicted WC/HC and a higher risk of PE (OR = 1.929 per 1 SD increase in WC, 95% CI = 1.339-2.778, p < 0.001; OR = 1.431 per 1 SD increase in HC, 95% CI =1.095-1.869; p = 0.009, respectively).

CONCLUSION

 There is a significant causal relationship between WC/HC and VTE/PE, which is consistent with observational studies. Taking measures to reduce WC/HC of obesity may help reduce the incidence of VTE/PE.

Evaluation of Activated Protein C Resistance Using Thrombin Generation Test

Activated protein C (APC) resistance (APCR) has been identified as a risk factor of venous thromboembolism (VTE). A mutation at the level of factor (F) V has at first permitted the description of this phenotypic pattern and corresponded to a transition (guanine to adenine) at nucleotide 1691 in the gene coding for factor V, resulting in the replacement of arginine at position 506 by a glutamine. This confers to this mutated FV a resistance toward the proteolytic action of the complex formed by activated protein C with protein S. However, many other factors also lead to APCR, such as other F5 mutations (e.g., FV Hong Kong and FV Cambridge), protein S deficiency, elevated factor VIII, exogenous hormone use, pregnancy, and postpartum. All these conditions lead to the phenotypic expression of APCR and are associated with an increased risk of VTE. Considering the large population affected, the proper detection of this phenotype is a public health challenge. Currently, two types of tests are available: clotting time-based assays and their multiple variants and a thrombin generation-based assays and the endogenous thrombin potential (ETP)-based APCR assay. As APCR was thought to be uniquely related to the FV Leiden mutation, clotting time-based assays were specifically designed to detect this inherited condition. Nevertheless, other APCR conditions have been reported but were not captured by these clotting methods. Thus, the ETP-based APCR assay has been proposed as a global coagulation test able to these multiple APCR conditions, as it provides much more information, which makes it a potential candidate for screening coagulopathic conditions before therapeutic interventions. This chapter will describe the current method used for the realization of the ETP-based APC resistance assay.

Integrative analyses of genes about venous thromboembolism: An umbrella review of systematic reviews and meta-analyses

BACKGROUND

In recent years, many studies have found possible links between gene polymorphisms and venous thromboembolism (VTE). By identifying genetic risk factors before facing environmental risk factors such as surgical interventions and COVID-19 vaccination, we could rapidly respond to the risk of VTE. The aim of this study was to perform an umbrella review of genetic variants related to VTE. Integrative gene analysis of VTE was performed to identify critical genetic variations.

METHODS

This study conducted an umbrella review of systematic reviews and meta-analyses. All included studies were selected from the PubMed/MEDLINE database. To select eligible studies, the following variables were extracted: first author name; effect size of each study genetic variant; year of publication; the number of studies included in each article; ethnicity, sample size, P values, and heterogeneity estimates. To assess cumulative evidence in genetic epidemiology about effects of gene polymorphisms on VTE, Human Genome Epidemiology Network's Venice criteria were used. Methodological quality assessment was conducted with JBI Critical Appraisal Checklist for Systematic Reviews and Research Syntheses.

RESULTS

Genes provided in the present study with genetic variants associated with VTE were FVL (G1691A), Prothrombin (G20210A), MTHFR (C677T, A1298C), PAI-1 (4G/5G), factor VII activating protease (1601G > A), and endothelial protein C receptor (g.6936A_G, c.4600A_G). Among them, variants in FVL, Prothrombin, MTHFR, and PAI-1 showed high significance. Particularly, variants in Prothrombin (G20210A), MTHFR (C677T), and PAI-1 (4G/5G) had more than 2 types of model significance.

CONCLUSION

The present study performed a systematic review of genetic variants associated with VTE. Our results could lead to a more comprehensive understanding of VTE etiology. These results could give a strategy of prediagnosis about evaluating individual risks of VTE who might be exposed to environmental risk factors.

Risk factors for venous thromboembolism following fractures isolated to the foot and ankle fracture

OBJECTIVE

Venous thromboembolism (VTE) is an uncommon, but potentially morbid, complication following foot and ankle fractures. Current standard is to not administer thromboprophylaxis to patients with such injuries. Nonetheless, patient and fracture factors might affect this risk/benefit consideration. The goal of this study was to determine what patients are most at risk.

METHODS

The M53Ortho Pearldiver database was used to identify patients with fractures isolated to the foot and ankle that were treated non-operatively or operatively. Patients with pilon, other appendicular fractures remote from the foot and ankle, and other traumatic injuries were excluded. The 90-day occurrence of VTE was identified based on codes for deep vein thrombosis or pulmonary embolism. Characteristics of those patients who did and did not have VTEs were compared using chi-square analyses. Multivariate logistical regression was then performed to determined factors independently associated with VTE. Finally, timing of VTE relative to fracture was analyzed.

RESULTS

A total of 298,886 patients with isolated foot or ankle fractures were identified, of which 1,661 (0.56%) had VTE in the 90 days following fracture. In terms of timing, 27.3% occurred in the first week, and 49.8% occurred in the first three weeks. Independent risk factors for VTE included (in decreasing order):prior VTE (odd ratio [OR] = 25.44), factor V Leiden (OR = 24.34), active cancer (OR = 1.84), specific fracture relative to metatarsal fracture (multiple fractures [OR: 1.51], ankle fracture [OR = 1.51], and calcaneus fracture [OR = 1.24]), surgical treatment (OR = 1.41), male sex (OR = 1.19), greater Elixhauser index (OR = 1.05), and increasing age (OR:1.05 per decade) (p<0.05 for each).

CONCLUSIONS

The present study found that, although only 0.56% of isolated foot and ankle fractures had a VTE within ninety days. Defined risk factors, such as Factor V Leiden, prior VTE, surgical treatment, active cancer, specific fracture patterns, and surgical treatment significantly affected the odds of their occurrence.

Microsurgical Breast Reconstruction in Patients with Disorders of Hemostasis: Perioperative Risks and Management

BACKGROUND

Surgical and technological advances have resulted in the widespread adoption of microsurgical breast reconstruction. Many comorbidities that potentially might impair vasculature and wound healing are no longer considered contraindications for these procedures. However, some uncertainty still prevails regarding the perioperative management of patients with disorders of hemostasis.

METHODS

The authors combined a literature review with a retrospective chart review of patients with disorders of hemostasis who had undergone microsurgical breast reconstruction at the senior author's (J.F.) center between 2015 to 2020. Several disorders associated with thrombotic and/or hemorrhagic complications were identified, and a standardized risk assessment and management strategy was developed in cooperation with a hematologist.

RESULTS

Overall, 10 studies were identified comprising 29 patients who had a defined disorder of hemostasis and underwent microsurgical breast reconstruction. Seventeen microsurgical breast reconstructions were performed on 11 patients at the senior author's (J.F.) center. High factor VIII levels, heterozygous factor V Leiden, and heterozygous prothrombin mutation G20210A were the most common genetic or mixed genetic/acquired thrombophilic conditions. As expected, hereditary antithrombin, protein C, or protein S deficiencies were rare. Among hemorrhagic disorders, thrombocytopenia, platelet dysfunction, and von Willebrand disease or low von Willebrand factor levels were those factors most frequently associated with increased perioperative bleeding.

CONCLUSIONS

Patients should be screened for elevated risk of thrombosis or bleeding before undergoing microsurgical breast reconstruction, and positive screening should prompt a complete hematologic evaluation. Interdisciplinary management of these disorders with a hematologist is essential to minimize risks and to obtain optimal reconstructive results.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, IV.

Laboratory Testing for the Evaluation of Phenotypic Activated Protein C Resistance

Activated protein C (APC) resistance (APCR) is considered a risk factor of venous thromboembolism (VTE). The most common genetic disorder conferring APCR is a factor (F) V Leiden mutation, but many other factors are also implicated, such as other F5 mutations (e.g., FV Hong-Kong and FV Cambridge), protein S deficiency, elevated factor VIII, exogenous hormone use, pregnancy and postpartum, depending on how APCR is defined. Considering the large population affected, the detection of this phenotype is crucial. Two types of tests are currently available: clotting time-based assays (with several versions) and thrombin generation-based assays with the endogenous thrombin potential (ETP)-based assay. The purpose of this review is therefore to discuss the performances of these tests and the cases in which it would be appropriate to use one over the other. Initially, as APCR was thought to be solely related to the FV Leiden mutation, the objective was to obtain a 100% specific assay. Clotting-time based assays were thus specifically designed to detect this inherited condition. Later on, an APCR condition without a FV Leiden mutation was identified and highlighted as an independent risk factor of VTE. Therefore, the development of a less specific assay was needed and a global coagulation test was proposed, known as the ETP-based APCR assay. In light of the above, these tests should not be used for the same purpose. Clotting time-based assays should only be recommended as a screening test for the detection of FV mutations prior to confirmation by genetic testing. On the other hand, the ETP-based APC resistance assay, in addition to being able to detect any type of APCR, could be proposed as a global screening test as it assesses the entire coagulation process.

Laboratory Testing for the Evaluation of Phenotypic Activated Protein C Resistance

Activated protein C (APC) resistance (APCR) is considered a risk factor of venous thromboembolism (VTE). The most common genetic disorder conferring APCR is a factor (F) V Leiden mutation, but many other factors are also implicated, such as other F5 mutations (e.g., FV Hong-Kong and FV Cambridge), protein S deficiency, elevated factor VIII, exogenous hormone use, pregnancy and postpartum, depending on how APCR is defined. Considering the large population affected, the detection of this phenotype is crucial. Two types of tests are currently available: clotting time-based assays (with several versions) and thrombin generation-based assays with the endogenous thrombin potential (ETP)-based assay. The purpose of this review is therefore to discuss the performances of these tests and the cases in which it would be appropriate to use one over the other. Initially, as APCR was thought to be solely related to the FV Leiden mutation, the objective was to obtain a 100% specific assay. Clotting-time based assays were thus specifically designed to detect this inherited condition. Later on, an APCR condition without a FV Leiden mutation was identified and highlighted as an independent risk factor of VTE. Therefore, the development of a less specific assay was needed and a global coagulation test was proposed, known as the ETP-based APCR assay. In light of the above, these tests should not be used for the same purpose. Clotting time-based assays should only be recommended as a screening test for the detection of FV mutations prior to confirmation by genetic testing. On the other hand, the ETP-based APC resistance assay, in addition to being able to detect any type of APCR, could be proposed as a global screening test as it assesses the entire coagulation process.

Laboratory Testing for the Evaluation of Phenotypic Activated Protein C Resistance

Activated protein C (APC) resistance (APCR) is considered a risk factor of venous thromboembolism (VTE). The most common genetic disorder conferring APCR is a factor (F) V Leiden mutation, but many other factors are also implicated, such as other F5 mutations (e.g., FV Hong-Kong and FV Cambridge), protein S deficiency, elevated factor VIII, exogenous hormone use, pregnancy and postpartum, depending on how APCR is defined. Considering the large population affected, the detection of this phenotype is crucial. Two types of tests are currently available: clotting time-based assays (with several versions) and thrombin generation-based assays with the endogenous thrombin potential (ETP)-based assay. The purpose of this review is therefore to discuss the performances of these tests and the cases in which it would be appropriate to use one over the other. Initially, as APCR was thought to be solely related to the FV Leiden mutation, the objective was to obtain a 100% specific assay. Clotting-time based assays were thus specifically designed to detect this inherited condition. Later on, an APCR condition without a FV Leiden mutation was identified and highlighted as an independent risk factor of VTE. Therefore, the development of a less specific assay was needed and a global coagulation test was proposed, known as the ETP-based APCR assay. In light of the above, these tests should not be used for the same purpose. Clotting time-based assays should only be recommended as a screening test for the detection of FV mutations prior to confirmation by genetic testing. On the other hand, the ETP-based APC resistance assay, in addition to being able to detect any type of APCR, could be proposed as a global screening test as it assesses the entire coagulation process.

Combined Oral Contraceptives and Venous Thromboembolism: Review and Perspective to Mitigate the Risk

Many factors must be considered and discussed with women when initiating a contraceptive method and the risk of venous thromboembolism (VTE) is one of them. In this review, we discuss the numerous strategies that have been implemented to reduce the thrombotic risk associated with combined oral contraceptives (COCs) from their arrival on the market until today. Evidences suggesting that COCs were associated with an increased risk of VTE appeared rapidly after their marketing. Identified as the main contributor of this risk, the dosage of the estrogen, i.e., ethinylestradiol (EE), was significantly reduced. New progestins were also synthetized (e.g., desogestrel or gestodene) but their weak androgenic activity did not permit to counterbalance the effect of EE as did the initial progestins such as levonorgestrel. Numerous studies assessed the impact of estroprogestative combinations on hemostasis and demonstrated that women under COC suffered from resistance towards activated protein C (APC). Subsequently, the European Medicines Agency updated its guidelines on clinical investigation of steroid contraceptives in which they recommended to assess this biological marker. In 2009, estradiol-containing COCs were marketed and the use of this natural form of estrogen was found to exert a weaker effect on the synthesis of hepatic proteins compared to EE. In this year 2021, a novel COC based on a native estrogen, i.e., estetrol, will be introduced on the market. Associated with drospirenone, this preparation demonstrated minor effects on coagulation proteins as compared with other drospirenone-containing COCs. At the present time, the standard of care when starting a contraception, consists of identifying the presence of hereditary thrombophilia solely on the basis of familial history of VTE. This strategy has however been reported as poorly predictive of hereditary thrombophilia. One rationale and affordable perspective which has already been considered in the past could be the implementation of a baseline screening of the prothrombotic state to provide health care professionals with objective data to support the prescription of the more appropriate contraceptive method. While this strategy was judged too expensive due to limited laboratory solutions, the endogenous thrombin potential-based APC resistance assay could now represent an interesting alternative.

Examination of in Factor V Leiden and Prothrombin II Thrombophilic Mutations in Czech Young Women Using ddPCR-Prevalence and Cost-Benefit Analysis

BACKGROUND

Thrombophilic mutations in genes for factor V Leiden and factor II prothrombin are among the most important risk factors for developing the thromboembolic disease (TED), along with the use of oral contraceptives (OCs) or smoking.

AIM

This study aimed to investigate the occurrence of risk factors in young women using droplet digital PCR (ddPCR) and, based on the results of this investigation, to perform a cost-benefit analysis of ddPCR-based screening in young women starting to take OCs compared to the treatment costs of patients who develop preventable TED in the Czech Republic.

METHODS

In this cross-sectional study, female university students filled in a questionnaire and provided a blood sample for DNA isolation and ddPCR analysis of both aforementioned genetic risk factors. The results, along with data from literature and web search, were used for cost-benefit analysis valid for the Czech Republic.

RESULTS

Out of 148 participants, 30 (20%) were smokers and 49 (33%) took OCs. A mutation was confirmed in 6 women (4.1%) in the factor V gene and in 3 women (2%) in the factor II gene, respectively. A model calculation on a cohort of 50,000 women starting to use contraceptives in the Czech Republic every year showed that at maximum compliance, (i.e., non-use of OC and smoking cessation), screening could prevent 68 cases of TED over the course of the mean period of OC use (5.7 years). Economically, the costs of testing in this cohort (2.25 mil. USD) would be significantly lower than prevented treatment costs (16 mil. USD at maximum compliance); the cost-benefit break-even point would be at 14.1% compliance.

CONCLUSION

The cost-benefit analysis based on our results indicates that screening for factor V Leiden and factor II prothrombin in young women before starting to use OCs would, in the conditions of the Czech Republic, likely be highly economically effective.

Anticoagulation Treatment in Venous Thromboembolism: Options and Optimal Duration

Venous thromboembolism (VTE), clinically presenting as deep-vein thrombosis (DVT) or pulmonary embolism (PE), constitutes a major global healthcare concern with severe complications, long-term morbidity and mortality. Although several clinical, genetic and acquired risk factors for VTE have been identified, the molecular pathophysiology and mechanisms of disease progression remain poorly understood. Anticoagulation has been the cornerstone of therapy for decades, but there still are uncertainties regarding primary and secondary VTE prevention, as well as optimal therapy duration. In this review we discuss the role of factor Xa in coagulation cascade and the different choices of anticoagulation therapy based on patients' predisposing risk factors and risk of event recurrence. Further, we compare newer agents to traditional anticoagulation treatment, based on most recent studies and guidelines.

'Pulmonary thrombosis in situ': risk factors, clinic characteristics and long-term evolution

: Pulmonary embolism typically occurs from deep venous thrombosis (DVT). However, not always a DVT can be identified, and 'in situ' generation of pulmonary embolism has been considered, referred to in the literature as 'De novo pulmonary embolism' (DNPE). The objective of the study is to assess risk factors, comorbidities, clinic characteristics and long-term evolution of patients with pulmonary embolism in the absence of an identified source. Retrospective study of 280 patients with pulmonary embolism, 190 pulmonary embolisms with DVT group and 90 (32%) pulmonary embolism without DVT (DNPE group), admitted to an Internal Medicine Department of a tertiary hospital from January 2012 to December 2015. In the DNPE group, segmental and subsegmental arteries were more frequently affected (P = 0.01). As compared with pulmonary embolisms with DVT group: older age, female sex, sedentary lifestyle, diabetes mellitus, arterial hypertension, heart failure, respiratory infections and chronic obstructive pulmonary disease (COPD) were significantly more frequent in DNPE. In multivariate analysis, respiratory infection [odds ratio (OR) 12.2, P < 0.0001], COPD (OR 8.7, P < 0.0001) and female sex (OR 3.0, P = 0.003) were independently associated risk factors. Long-term mortality (median follow-up 15 months) was also higher in DNPE group (34 vs. 16%, P = 0.01). De novo pulmonary embolism occurred in 32% of cases of pulmonary embolisms and was more frequent in female and COPD patients or those with respiratory infections as compared with pulmonary embolisms in which DVT was identified as a source of embolism.

Prevalence of thrombophilia-associated genetic risk factors in blood donors of a regional hospital in southern Brazil

Introduction

Thromboembolic events occur due to an imbalance in the hemostasis and some factors associated with this condition can be inherited. In order to evaluate the frequency of genotypes considered to be common hereditary risk factors for thrombophilia associated with venous thrombosis (g.1691G > A and g.20210G > A) and hyperhomocysteinemia (g.677C > T and g.1298A > C), samples from voluntary healthy blood donors at the Hospital de Clínicas de Porto Alegre were tested.

Methods

We examined 325 blood samples from blood donors collected from October 2017 to July 2018. Blood was collected on filter paper and the DNA was extracted for single nucleotide polymorphisms (SNPs) analysis using the qualitative real time polymerase chain reaction.

Results

The calculated frequencies of each genetic variant in heterozygosity were 4% for the FV gene (g.1691G > A), 4% for the F2 gene (g.20210G > A) and 42% and 39% for methylenetetrahydrofolate reductase (MTHFR), g.677C > T and g.1298A > C, respectively. Only the genetic variants of MTHFR were found in homozygosity, with frequencies of 14% and 6% (g.677C > T and g.1298A > C), respectively.

Discussion

Altogether, these results describe the frequencies of genetic variants associated with venous thrombosis and hyperhomocysteinemia in the analyzed group and are important to enhance our current knowledge about the genetic profiles of Brazilian blood donors.

Thrombotic risk in antiphospholipidic syndrome: From hypothesis to current evidence (Review)

Thirty-five years after it was first described, antiphospholipid syndrome (APS) is unanimously recognized as a systemic autoimmune disease, a major acquired thrombophilia, which can affect any arterial or venous vascular territory, explaining the great diversity of clinical manifestations. The current classification criteria updated in the International Consensus Statement for Definite Antiphospholipid Syndrome from Sydney cannot explain alone the unpredictable evolution with thrombotic events of the patients diagnosed with APS. Although the link to genetics and epigenetics has not been clearly defined as in other autoimmune diseases, it is clear that a proper stratification of thrombotic risk in the era of personalized medicine must include classic biological markers (antiphospholipid antibodies, aPL), along with the already recognized phenotypes, non-conventional serological markers, and additional genetic risk factors for thrombosis. Moreover, with advancing age, a patient with APS develops other thrombotic risk factors which include: hypertension and dyslipidemia among others. According to the classification criteria, a patient is considered to have a low, moderate or high thrombotic risk. In clinical practice, patients with the same risk score may have completely different evolutions in terms of the recurrence of thrombosis. Concerning this approach, it appears that new non-conventional serological markers, phenotype-assessment and genetic determinants have an increasing importance and should be reconsidered in a proper thrombotic risk evaluation in patients with APS, compared to the initial concept of APS as first defined.

Genetic Factors in Antiphospholipid Syndrome: Preliminary Experience with Whole Exome Sequencing

As in many autoimmune diseases, the pathogenesis of the antiphospholipid syndrome (APS) is the result of a complex interplay between predisposing genes and triggering environmental factors, leading to a loss of self-tolerance and immune-mediated tissue damage. While the first genetic studies in APS focused primarily on the human leukocytes antigen system (HLA) region, more recent data highlighted the role of other genes in APS susceptibility, including those involved in the immune response and in the hemostatic process. In order to join this intriguing debate, we analyzed the single-nucleotide polymorphisms (SNPs) derived from the whole exome sequencing (WES) of two siblings affected by APS and compared our findings with the available literature. We identified genes encoding proteins involved in the hemostatic process, the immune response, and the phospholipid metabolism (PLA2G6, HSPG2, BCL3, ZFAT, ATP2B2, CRTC3, and ADCY3) of potential interest when debating the pathogenesis of the syndrome. The study of the selected SNPs in a larger cohort of APS patients and the integration of WES results with the network-based approaches will help decipher the genetic risk factors involved in the diverse clinical features of APS.

Anticoagulation Therapy in a Patient With Heterozygous Factor V Leiden and Coexisting Homozygous Prothrombin Gene Mutations

Coexistent heterozygous factor V Leiden and homozygous prothrombin G20210A gene mutations is a rare and potentially life-threatening occurrence. This inherited thrombophilia often presents as non-specific venous thromboemboli and can mimic a variety of emergent medical conditions. The pathophysiology of the disease has been well documented; however, long-term treatment efficacy remains poorly understood. We report the case of a 25-year-old male presenting with acute chest pain. A comprehensive workup revealed bilateral pulmonary emboli arising in part from concomitant heterozygous factor V Leiden and homozygous prothrombin G20210A gene mutations. Immediate and continuous treatment with anticoagulants enoxaparin and apixaban significantly reduced the patient’s symptoms and D-dimer within one week. This case provides insight into an effective treatment regimen for this rare and inherited thrombophilia.

Oral Contraceptives and Venous Thromboembolism: Focus on Testing that May Enable Prediction and Assessment of the Risk

Combined oral contraceptives (COCs) induce several changes in the levels of coagulation factors. The levels of procoagulant factors are often increased, while levels of anticoagulant factors are decreased. Fibrinolysis is also affected, even if the effect seems to be more counterbalanced by opposite regulation of profibrinolytic and antifibrinolytic factors. These effects on hemostasis are more pronounced with third- or fourth-generation COC compared with second-generation COC. Venous thromboembolism (VTE) risk increases when multiple risk factors, including genetic and environmental, are present simultaneously. COC use causes changes in coagulation that modify the prothrombotic state induced by preexisting hemostatic alterations in a supra-additive manner. Therefore, testing appears to be of importance not only before implementing COC but also to monitor any potential thrombogenicity induced by COC therapy. Inherited genetic factors, such as factor V Leiden, G20210A prothrombin mutation, antithrombin, protein C or protein S deficiencies, non-O blood group, as well as CYP2C9*2 and the rs4379368 mutations, have all been identified as genetic predictive risk factors of VTE in women. Nevertheless, the screening of these genetic biomarkers is not capable of assessing the phenotypic expression of the risk. This review will focus on the different options for screening the thrombogenic status in this population. Specific attention will be given to the endogenous thrombin potential-based activated protein C resistance, a test aiming at assessing the thrombogenicity induced by hormonal therapies and inherited or acquired thrombophilia.

Meta-analysis of the relationship between methylenetetrahydrofolate reductase C677T and A1298C polymorphism and venous thromboembolism in the Caucasian and Asian

Recent years, it is a highly debated topic that whether methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and A1298C polymorphism could increase susceptibility to venous thromboembolism (VTE) in the Asian and Caucasian. Therefore, we expect to settle that controversy evidentially. Basic methods: Electronic databases (Pubmed, embase, Cochrane library, scopus, OvidSP, Wiley Online library, Springer link, EBSCO, Elsevier Science Direct, Google scholar) without date limitation were searched. Crude odds ratio (OR) along with 95% confidence interval (95% CI) was calculated to assess the association quantitatively. Finally, a total of 37 eligible studies were included, containing 31 for MTHFR C677T polymorphism and 6 for MTHFR A1298C polymorphism. The pooled results suggested that MTHFR C677T mutation may increase susceptibility to VTE in reverse recessive model (CC+CT vs TT): OR = 0.68 (0.56, 0.83), reverse dominant model (CC vs CT +TT): OR = 0.82 (0.72, 0.94), heterozygote model (CT vs TT): OR = 0.65 (0.52, 0.81), homozygote model (CC vs TT): OR = 0.73 (0.60, 0.89) and allele model (C vs T): OR = 0.80 (0.71, 0.90). Subgroup analysis about Asian also support that results, but Caucasian group not. In addition, MTHFR A1298C polymorphism may be not related to VTE in all genetic model. The results of meta-analysis indicated that MTHFR C677T polymorphism might increase the risk of VTE, especially in Asian population.

DVT and Pulmonary Embolism Following Knee Arthroscopy: The Role of Genetic Predisposition and Autoimmune Antibodies: A Report of 3 Cases

Deep vein thrombosis (DVT) after arthroscopy has been considered a rare event; however, recent studies using ultrasound and venography have shown that the incidence of DVTs is underestimated. CASES:: This report describes 3 patients with DVT and/or PE after knee arthroscopy who were attributed to a genetic predisposition of hypercoagulability unknown to the patient and surgeon. CONCLUSIONS:: Genetic predisposition and autoimmune antibodies may play a role in the development of DVT after knee arthroscopy. We recommend focused questions regarding family history be added to the standard DVT/PE preoperative questionnaire.

Molecular Analysis of Prothrombotic Gene Variants in Venous Thrombosis: A Potential Role for Sex and Thrombotic Localization

Background: Requests to test for thrombophilia in the clinical context are often not evidence-based. Aim: To define the role of a series of prothrombotic gene variants in a large population of patients with different venous thromboembolic diseases. Methods: We studied Factor V Leiden (FVL), FVR2, FII G20210A, Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, beta-fibrinogen -455 G>A, FXIII V34L, and HPA-1 L33P variants and PAI-1 4G/5G alleles in 343 male and female patients with deep vein thrombosis (DVT), 164 with pulmonary embolism (PE), 126 with superficial vein thrombosis (SVT), 118 with portal vein thrombosis (PVT), 75 with cerebral vein thrombosis (CVT) and 119 with retinal vein thrombosis (RVT), and compared them with the corresponding variants and alleles in 430 subjects from the general population. Results: About 40% of patients with DVT, PE and SVT had at least one prothrombotic gene variant, such as FVL, FVR2 and FII G20210A, and a statistically significant association with the event was found in males with a history of PE. In patients with a history of PVT or CVT, the FII G20210A variant was more frequent, particularly in females. In contrast, a poor association was found between RVT and prothrombotic risk factors, confirming that local vascular factors have a key role in this thrombotic event. Conclusions: Only FVL, FVR2 and FII G20210A are related to vein thrombotic disease. Other gene variants, often requested for testing in the clinical context, do not differ significantly between cases and controls. Evidence of a sex difference for some variants, once confirmed in larger populations, may help to promote sex-specific prevention of such diseases.

Protein C Deficiency as a Risk Factor for Stroke in Young Adults: A Review

Protein C (PC) is a 62-kD vitamin K dependent glycoprotein produced by the liver as a zymogen and is activated by binding to the thrombin-thrombomodulin complex, with protein S (PS) acting as a cofactor. Among its various functions, PC acts as a naturally occurring anticoagulant and its deficiency, either homozygous or heterozygous, predisposes the individual to a state of thrombosis, particularly venous thromboembolism, and mainfests as myocardial infarction (MI), deep venous thrombosis, pulmonary embolism, or stroke. This review discusses the pathophysiology of the anticoagulatory effect of PC, mode of inheritance of its deficiency, the arterial and venous involvement in patients with stroke, and its risk factors. A detailed analysis of published case reports on PC deficiency as a causative agent of stroke in young adults has also been included along with the management of such patients.

Therapeutic Implications of Inherited Thrombophilia in Pregnancy

BACKGROUND

Inherited (hereditary) thrombophilia is a genetic disorder that affects coagulation, being responsible for more than 60% of idiopathic (spontaneous or unprovoked) thromboembolic events. Association of inherited thrombophilia with pregnancy increases the risk of thromboembolic disease, and it may be related to many complications, such as preeclampsia, recurrent miscarriage intrauterine growth restriction, early detachment of placenta, and prematurity.

AREAS OF UNCERTAINTY

Interpretation of a positive test for thrombophilia in pregnant women is difficult because they have many natural changes in the coagulation system. Genetic diagnosis of thrombophilia, after a thrombotic event or during a pregnancy complication, has a major importance, not only to define its etiology but also to determine the duration of anticoagulant treatment and risk stratification for prophylaxis treatment.

DATA SOURCES

Literature search was performed using electronic database (PubMed) between April 1981 and November 2018. We used different keywords and MeSH terms to generate the most relevant results related to the inherited thrombophilia and its impact on pregnancy.

RESULTS

Screening for inherited thrombophilia in young women is recommended in case of personal history of venous thromboembolism, first-degree relatives with a history of high-risk thrombophilia, or personal history of second-trimester miscarriage. Decision to recommend thromboprophylaxis with anticoagulant treatment in pregnant women with inherited thrombophilia is determined by history of venous thromboembolism, type and associated risk of inherited thrombophilia, and presence of additional risk factors. Low-molecular-weight heparins are the preferred agents for prophylaxis in pregnancy, while the doses vary depending on thrombophilia type, personal history, and associated risk factors.

CONCLUSIONS

Association between 2 procoagulant conditions, inherited thrombophilia and pregnancy, has an important impact for the mother and fetus. This review will summarize the impact of each inherited prothrombotic factor on cardiovascular and pregnancy outcomes and will discuss the role of anticoagulation treatment for women diagnosed with inherited thrombophilia.

Association of SERPINC1 Gene Polymorphism (rs2227589) With Pulmonary Embolism Risk in a Chinese Population

Background and Aims: Genetic variants in the gene SERPINC1 have been shown to be associated with antithrombin deficiency, which subsequently contributes to the susceptibility to venous thrombosis. However, several other studies have shown conflicting results regarding the association of SERPINC1 gene polymorphisms (rs2227589) with the risk of thrombosis. Hence, in the present study, we conducted a case-control study to further evaluate the association between the variant rs2227589 with antithrombin deficiency in pulmonary embolism (PTE). A pooled systematic analysis was also conducted to evaluate the risk of rs2227589 in venous thromboembolism (VTE) among multiple populations. Methods: This case-control study involved 101 patients and 199 healthy controls. The allele frequency of SERPINC1 variant rs2227589 was analyzed by Sequenom assay. Antithrombin anticoagulant activity was detected using an automatic coagulation analyzer. In addition, a pooled systematic analysis on 10 cohorts consisting of 5,518 patients with VTE and 8,935 controls was performed. Results: In total, 27 (26.7%) PTE subjects were diagnosed as having antithrombin deficiency. Our results showed that antithrombin plasma activity was slightly lower in T allele carriers than that in C allele carriers. However, there was no significant correlation between rs2227589 genotype and antithrombin anticoagulant activity. The recessive model showed that rs2227589 was significantly associated (p = 0.026) with an increased risk {odds ratio [OR]: 2.31, 95% confidence interval [CI] (1.09-4.89)} of Chinese PTE. The pooled systematic analysis of all case-control study and meta-analysis showed that rs2227589 polymorphism was associated with an increased risk of VTE in the additive model [OR: 1.09, 95% CI (1.01-1.18), P = 0.029] and dominant model [OR: 1.10, 95% CI (1.01-1.20), P = 0.034]. Conclusions: Our study demonstrated that variant rs2227589 is associated with an increased risk of PTE in a Chinese population but no correlation with antithrombin anticoagulant activity. However, pooled systematic analysis of multiple populations showed a significant association between rs2227589 and the risk of VTE in the additive and dominant genetic model.

Identifying mutation-driven changes in gene functionality that lead to venous thromboembolism

Venous thromboembolism (VTE) is a common hematological disorder. VTE affects millions of people around the world each year and can be fatal. Earlier studies have revealed the possible VTE genetic risk factors in Europeans. The 2018 Critical Assessment of Genome Interpretation (CAGI) challenge had asked participants to distinguish between 66 VTE and 37 non-VTE African American (AA) individuals based on their exome sequencing data. We used variants from AA VTE association studies and VTE genes from DisGeNET database to evaluate VTE risk via four different approaches; two of these methods were most successful at the task. Our best performing method represented each exome as a vector of predicted functional effect scores of variants within the known genes. These exome vectors were then clustered with k-means. This approach achieved 70.8% precision and 69.7% recall in identifying VTE patients. Our second-best ranked method had collapsed the variant effect scores into gene-level function changes, using the same vector clustering approach for patient/control identification. These results show predictability of VTE risk in AA population and highlight the importance of variant-driven gene functional changes in judging disease status. Of course, more in-depth understanding of AA VTE pathogenicity is still needed for more precise predictions.

A prospective cohort study to identify and evaluate endotypes of venous thromboembolism: Rationale and design of the Genotyping and Molecular Phenotyping in Venous ThromboEmbolism project (GMP-VTE)

Several clinical, genetic and acquired risk factors for venous thromboembolism (VTE) have been identified. However, the molecular pathophysiology and mechanisms of disease progression remain poorly understood. This is reflected by uncertainties regarding the primary and secondary prevention of VTE and the optimal duration of antithrombotic therapy. A growing body of literature points to clinically relevant differences between VTE phenotypes (e.g. deep vein thrombosis (DVT) versus pulmonary embolism (PE), unprovoked versus provoked VTE). Extensive links to cardiovascular, inflammatory and immune-related morbidities are testament to the complexity of the disease. The GMP-VTE project is a prospective, multi-center cohort study on individuals with objectively confirmed VTE. Sequential data sampling was performed at the time of the acute event and during serial follow-up investigations. Various data levels (e.g. clinical, genetic, proteomic and platelet data) are available for multi-dimensional data analyses by means of advanced statistical, bioinformatic and machine learning methods. The GMP-VTE project comprises n = 663 individuals with acute VTE (mean age: 60.3 ± 15.9 years; female sex: 42.8%). In detail, 28.4% individuals (n = 188) had acute isolated DVT, whereas 71.6% subjects (n = 475) had PE with or without concomitant DVT. In the study sample, 28.9% (n = 129) of individuals with PE and 30.1% (n = 55) of individuals with isolated DVT had a recurrent VTE event at the time of study enrolment. The systems-oriented approach for the comprehensive dataset of the GMP-VTE project may generate new biological insights into the pathophysiology of VTE and refine our current understanding and management of VTE.

Impact of progestogens on hemostasis

Combined hormonal contraception containing estrogen and progestogen and postmenopausal hormone therapy with estrogen ± progestogen are reported risk factors for venous thrombosis. The thrombotic risk varies by estrogen dose and type of progestogen. Estrogen combined with "newer generation" progestogens in combined oral contraceptives may have higher thrombotic risk than estrogen combined with older generation progestogens. Among postmenopausal women thrombotic risk also varies by type of hormone and mode of delivery. Although the risk of thrombosis with the different hormonal compounds is uncertain, it has definitely been attributed to the pharmacological effect of the hormones on hemostasis. Animal and cell culture studies have demonstrated the pharmacodynamics of progestogens with respect to hemostasis. Extrapolation from these studies to clinical conditions and further to clinical end points such as cardiovascular disease is, however, controversial. Few clinical studies have focused on the effect of progestogen only therapy on the hemostatic system in vivo. Most of the current knowledge regarding the in vivo effect of progestogens on hemostasis is obtained from studies with combined contraceptives. These results obviously reflect the combined influence of both estrogen and progestogen on hemostasis, and extrapolation to progestogen-only conditions is challenging. This paper discusses the pharmacodynamics of progestogens in relation to the hemostatic system, addressing results obtained in animal and cell culture studies and in clinical studies employing progestogen-only and combined oral contraceptives. The compiled results suggest that the major effect of progestogens on hemostasis is related to alterations in platelet function and the tissue factor pathway of coagulation. More studies focusing on these topics are warranted.

Association of the CYP4V2 polymorphism rs13146272 with venous thromboembolism in a Chinese population

Genome-wide association studies have identified the CYP4V2 polymorphism (rs13146272) as a risk factor associated with venous thromboembolism (VTE). However, due to the small sample size and variance in genetic analysis models, the relationship between VTE and rs13146272 remains unclear. Here, we performed a case-control study to analyse the associations between rs13146272 and VTE in a Chinese population and to compare the differences among various ethnicities. In this study, 226 VTE patients and 205 healthy controls were recruited, and the allele frequency of variant rs13146272 was analysed by a MassARRAY SNP genotyping assay. In addition, 9 case-control cohorts from 5 studies involving 6667 VTE-affected individuals and 8716 control subjects were included in this meta-analysis. Pooled ORs and 95% CIs were calculated to assess the association between rs13146272 and VTE by using different genetic models. Our case-control study results showed that there was no significant association between VTE and rs13146272 under the additive model (OR = 0.92, 95% CIs: 0.70-1.21, p = 0.55) in this Chinese population. However, the results of the meta-analysis performed by merging all cohorts showed that rs13146272 was significantly associated with VTE under the additive model, recessive model and dominant model. In the additive and recessive models, the association reached the threshold for genome-wide significance (p < 5.0e^-08). In conclusion, our pooled systematic study results indicated that individuals with the A allele had a higher risk of developing VTE than those with the C allele of the rs13146272 variant, but the risk was inconsistent among different ethnicities. Further validation of this association with larger sample sizes and multiple ethnicities is warranted.

Prevalence and geographical variation of Factor V Leiden in patients with cerebral venous thrombosis: A meta-analysis

Background

Previous results regarding the prevalence of Factor V Leiden (FVL) in patients with cerebral venous thrombosis (CVT) varied remarkably. Therefore, we performed a meta-analysis to evaluate the potential association between FVL and CVT.

Methods

The PubMed, Embase, Cochrane Central Register of Controlled Trials, and Web of Science were searched for relevant case-control studies. The data were pooled for analysis of the association between FVL and CVT with a random-effects model. Subgroup and sensitivity analyses were performed to evaluate the robustness of the results. Publication bias was assessed by funnel plot and the Egger’s test.

Results

A total of 39 case-control studies including 1807 cases of CVT and 7699 control cases were included. FVL was more common in patients with CVT (195/1822) than in controls(369/7795), [odds ratio(OR) = 2.70, 95% confidence interval(CI) 2.16–3.38, P < 0.00001]. Results of subgroup analyses indicated that the association between FVL and CVT varied according to geographic regions. The associations between FVL and CVT were significant in studies from Germany (OR = 2.42, 95%CI 1.70–3.45, P < 0.00001), Brazil(OR = 2.82, 95%CI 1.24–6.42, P = 0.01), France (OR = 5.44, 95%CI 1.35–21.92, P = 0.02), Iran (OR = 6.61, 95%CI 1.83–23.93, P = 0.004), and Tunisia (OR = 6.54, 95%CI 2.89–14.82, P < 0.00001), but not in those from Italy (OR = 1.49, 95%CI 0.59–3.78, P = 0.40) or the US (OR = 2.37, 95%CI 0.59–9.42, P = 0.22).

Conclusion

FVL may be more common in patients with CVT. However, the association between FVL and CVT varied depending on the geographic origin of the studies.

Venous thromboembolism prophylaxis after hip preservation surgery: a review and presentation of institutional experience

Venous thromboembolism (VTE) is a serious complication after major orthopedic procedures. The best options for prevention of the VTE are still debated. The most popular evidence-based guidelines for prevention and treatment of VTE in orthopedic surgery addressed the total hip or knee arthroplasty and hip fractures as the major orthopedic surgeries. Majority of studies have evaluated the different modalities of the VTE prophylaxis in patients undergiong hip or knee arthroplasty. Hip preservation surgeries (HPS) including mini-open femoroacetabular osteoplasty, surgical dislocation of the hip, arthroscopic procedures, and periacetabular osteotomy (PAO) are gained popularity in recent two decades. The majority of these patients are young, healthy and active and may not be considered at high risk for VTE. The frequency of VTE in patients undergoing PAO seems to be low between 0 and 5%. There is a paucity of data regarding rates of VTE in young healthy patients undergoing HPS as well as the optimal prevention methods for VTE. Hence current VTE prevention guidelines do not cover HPS adequately. We aimed to review the available literature regarding VTE events and VTE prophylaxis options after HPS. We discussed the available and potential options for prophylaxis of VTE events in these procedures along with our experience in a large cohort of hip preservation surgery.