Testing for thrombophilia: an evidence-based approach

Genetic landscape of thrombophilia in recurrent miscarriages

The etiology of recurrent miscarriage (RM) is extremely heterogeneous, encompassing genetic, immunological, anatomical, endocrine, thrombophilic, infectious, and uterine abnormalities. Thrombophilia is a major contributor to pregnancy complications, potentially harming the fetus and jeopardizing the continuation of pregnancy. Therefore, successful pregnancy outcomes depend on maintaining a delicate balance between coagulation and fibrinolytic factors, crucial for ensuring the adjustment of the basal plate to facilitate adequate placental perfusion. Despite numerous studies shedding light on the role of thrombophilic factors and genetic variations in RM, the exact pathogenesis remains unclear. It is imperative to systematically rule out thrombophilia and other related factors responsible for pregnancy disorders and RMs to guide appropriate and active management strategies. Addressing thrombophilia continues to present challenges in terms of effective treatment. The current review aims to address the heterogeneity of RM as a therapeutic challenge, emphasizing the need for standardized diagnostic tests and welldesigned multicenter research trials to gather robust, evidence-based data on thrombophilic causes of RM and provide effective treatment. The goal is to enhance the understanding of thrombophilic factors and genetic landscapes associated with RM through various approaches, including candidate gene studies, genome-wide association studies, and high-throughput sequencing. Meta-analyses have underscored the significance of genetic aberrations in RM, highlighting the necessity for identifying critical mutations implicated in the etiopathogenesis of miscarriages to pave the way for implementation of targeted clinical therapies.

The Etiology of the Thrombotic Phenomena Involved in the Process of Coronary Artery Disease-What Is the Role of Thrombophilic Genes in the Development of This Pathology?

Cardiovascular diseases, among which includes coronary artery disease, represent one of the most important causes of mortality and morbidity worldwide. Research aimed at determining the risk factors involved recognizes a group of "traditional" risk factors, but also more recent studies identified over 100 "novel" ones which may have a role in the disease. Among the latter is the thrombophilia profile of a patient, a pathology well-established for its involvement in venous thromboembolism, but with less studied implications in arterial thrombosis. This paper reviews the literature, explaining the pathophysiology of the thrombophilia causes associated most with coronary thrombosis events. Results of several studies on the subject, including a meta-analysis with over 60,000 subjects, determined the significant involvement of factor V Leiden, prothrombin G20210A mutation, plasminogen activator inhibitor-1 and antiphospholipid syndrome in the development of coronary artery disease. The mechanisms involved are currently at different stages of research, with some already established and used as therapeutic targets.

SERPINC1 c.1247dupC: a novel SERPINC1 gene mutation associated with familial thrombosis results in a secretion defect and quantitative antithrombin deficiency

BACKGROUND

Antithrombin (AT) is an important anticoagulant in hemostasis. We describe here the characterization of a novel AT mutation associated with clinically relevant thrombosis. A pair of sisters with confirmed type I AT protein deficiency was genetically analyzed on suspicion of an inherited SERPINC1 mutation. A frameshift mutation, c.1247dupC, was identified and the effect of this mutation was examined on the cellular and molecular level.

METHODS

Plasmids for the expression of wild-type (WT) and mutated SERPINC1 coding sequence (CDS) fused to green fluorescent protein (GFP) or hemagglutinin (HA) tag were transfected into HEK293T cells. Subcellular localization and secretion of the respective fusion proteins were analyzed by confocal laser scanning microscopy and Western blot.

RESULTS

The c.1247dupC mutation results in a frameshift in the CDS of the SERPINC1 gene and a subsequently altered amino acid sequence (p.Ser417LysfsTer48). This alteration affects the C-terminus of the AT antigen and results in impaired secretion as confirmed by GFP- and HA-tagged mutant AT analyzed in HEK293T cells.

CONCLUSION

The p.Ser417LysfsTer48 mutation leads to impaired secretion, thus resulting in a quantitative AT deficiency. This is in line with the type I AT deficiency observed in the patients.

Reducing inappropriate inpatient thrombophilia testing through an electronic health record intervention

Current literature does not support routine testing for hereditary and acquired thrombophilia disorders in the inpatient setting. Testing in the acute setting rarely changes patient management or could lead to patient mismanagement. Despite prior educational interventions, continued overuse of inpatient testing warrants further quality improvement measures. A hard-stop best practice advisory pop-up was implemented in the electronic medical record in a multicenter academic hospital system to provide clinicians guidance on the appropriate use of thrombophilia testing at the point of care. Pre- and postintervention retrospective data were collected to assess clinical features before and after implementation. Before the intervention, 271 patients underwent inpatient hypercoagulability testing; after the intervention, 238 patients underwent inpatient hypercoagulability testing. The total number of labs ordered per patient decreased from 1185 to 910, a 13% reduction (P = 0.003). Overall, there was a savings of $23,597 in total direct cost and $123,153 in total charges when comparing the 6-month timeframes before and after the intervention (P < 0.01). Although this study found only mild reductions in thrombophilia testing, it presents a new means of providing point-of-care intervention and education for hypercoagulability testing in the inpatient setting.

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.

Genomic Analysis of Thrombophilia Variants in the General Population for the Creation of an Effective Preoperative Screening Tool

BACKGROUND

 The loss of a free flap in reconstructive microsurgery is a devastating complication in both the intraoperative and postoperative setting. Previous research has identified a variety of genetic polymorphisms that induce a hypercoagulable state and predispose patients to clot formation and subsequent free flap loss. We aim to review the risks of performing microsurgery on patients who are genetically predisposed to hypercoagulability, as well as identify options, for preoperative screening of inherited thrombophilia.

METHODS

 A thorough literature review was conducted with an online database. A total of 30 studies were reviewed to identify genetic polymorphisms that cause inherited thrombophilia. Through manual review of the literature, a table was created that included thrombotic risk factors and their associated genetic polymorphisms. If the information was available, prevalence for each thrombotic risk was also reported.

RESULTS

 Overall, 18 thrombotic risk factors that contribute to hereditary thrombophilia were identified and linked with specific genes and/or genetic polymorphisms. In studies that did not look at particular ethnic groups, 13 unique thrombotic risk factors were identified. In studies that examined specific ethnic groups exclusively, 12 thrombotic risk factors were identified and related to their respective gene or group of genes. Five of the 18 thrombotic risk factors identified were associated with increased risks of both venous and arterial thrombosis. The remainder of the thrombotic risk factors was associated with increased risk of venous thrombosis exclusively.

CONCLUSION

 The use of genetic screening tests for hereditary thrombophilia in the preoperative setting can serve as an effective preventative measure against postoperative thrombosis. Further exploration of thrombotic risk factors and their related genetic polymorphisms are important steps in reducing postoperative free flap loss.

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.

Redox status of pregnant women with thrombophilia

Background/Aim. Since the role of oxidative stress in the pathogenesis of thrombophilia in pregnancy has still not been clarified, the aim of the study was to assess the redox status of pregnant women with thrombophilia. Methods. The study involved 120 pregnant women divided into two groups: pregnant women with thrombophilia (n = 60) and women with normal pregnancy (n = 60). Blood samples for biochemical analysis were collected at the end of the first, second, and third trimester of pregnancy. Concentrations of hydrogen peroxide (H2O2), nitrites (NO2-), and the index of lipid peroxidation measured as thiobarbituric acid reactive substances (TBARS) were measured in plasma. Levels of reduced glutathione (GSH), activities of superoxide dismutase (SOD) and catalase (CAT) were measured in erythrocytes. Results. In women with thrombophilia, NO2- values were increased in the first and third trimester compared to healthy pregnant women (p < 0.05). The higher levels of TBARS and H2O2 were noticed in women with thrombophilia in the first trimester compared to healthy pregnant women (p < 0.05). The values of SOD and CAT were lower in women with thrombophilia in the third and GSH in the first trimester compared to the control group (p < 0.05). Conclusion. Our results suggest an increased generation of prooxidants in thrombophilia at the beginning of gestation, which declines as gestation progresses and reaches similar values as in normal pregnancy at the end of pregnancy. Generally viewed, pregnant women with thrombophilia was associated with impaired antioxidant capacity ? activities of SOD and CAT were lower in the third and GSH in the first trimester compared to their values in healthy pregnant women.

Hemostasis Laboratory Diagnostics: Characteristics, Communication Issues, and Current Challenges Resulting from Centralization of Laboratory Medicine

Laboratory diagnostics of patients with bleeding and thrombotic disorders can be a delicate task, which requires special skills and expertise. In this article, characteristic features of hemostasis testing are reviewed, including staged protocols and synoptic assessment of the patient history, clinical symptoms, and laboratory findings. Despite major progress in the diagnostic and therapeutic management, centralized testing of hemostasis can be associated with substantial challenges, resulting from the current dissociation between the clinical and laboratory world. To address some of these challenges, possible solutions are discussed, including adaptation of an established working paradigm.

Prevalence and Outcomes of Thrombophilia in Patients with Acute Pulmonary Embolism

Background

We aimed to study the prevalence and outcomes of thrombophilia in acute pulmonary embolism.

Methods

A retrospective observational study was conducted to include patients with a radiologically confirmed diagnosis of PE screened for thrombophilia from May 2011 to February 2015. Data included patients’ demographics; clinical presentation, risk factors, laboratory investigations, management, and outcome were analyzed and compared in patients with and without thrombophilia.

Results

A total of 227 cases of PE were included in the study, of which 108 (47.6%) had thrombophilia. The most frequent coagulopathic abnormality included deficiency of protein S, protein C, and antithrombin III and hyperhomocysteinemia. Only seven out of 79 patients were found to have factor V Leiden. PE patients diagnosed with thrombophilia were 10 years younger in age and peaked in the age range 30–39 years. Prior history of DVT (p=0.001) and PE (p=0.001) were the main significant risk factors in the thrombophilia group. The frequency of different risk categories of clinical probability scores did not differ significantly among those with and without thrombophilia. Pulmonary hypertension was a common complication in the thrombophilia group (P=0.009). Medications used included warfarin (74.7%), enoxaparin (73.9%), and heparin (55.4%). The overall mortality rate was 8.4%, and was non-significantly higher in the non-thrombophilia group.

Conclusion

Deficiencies of protein S, protein C, and antithrombin III are the leading causes of thrombophilic defects. Patients with hereditary thrombophilia are at increased risk of acute PE, particularly among young individuals. Therefore, early detection of thrombophilic defects together with other unprovoked risk factors could reduce the risk of recurrent VTE.

Hypercoagulable workup in a community hospital setting: to test or not to test; that is the question

Background: Thrombophilia tests are often ordered unnecessarily and/or inappropriately, with significant impact on healthcare costs, hospital resources, time, and potential harm to the patient.

Objective: To identify the incidence of unnecessary and inappropriate thrombophilia testing in a community hospital setting.

Methods: We retrospectively reviewed electronic medical records for patients who underwent inpatient thrombophilia testing at The Brooklyn Hospital Center from 1/1/2018 to 12/31/2018. The indications, and details of the tests, and associated costs were recorded.

Results: A total of 62 patients were included (mean age 45.8, 67.7% female). In 57/62 (91.9%) patients, tests were ordered in the acute phase of thrombosis. At the time the tests were ordered, 29/62 (46.8%) patients were on anticoagulation. Positive results were found in 21/62 (53.2%) patients, but was repeated in only 1/21 (4.7%) patient. Results for 51/62 (82%) patients were obtained after discharge. The hematology-oncology service was consulted in 5/62 (8.1%) cases and recommended testing in only 1 (1.6%) patient. Only 1 (1.6%) patient had both an appropriate indication and appropriate testing. Costs for the 273 total tests were $26,400.

Conclusion: Thrombophilia tests were often ordered inappropriately and unnecessarily. We recommend testing only for patients with inpatient status under recommendation from the hematology-oncology service.

Patient experience and utility of genetic information: a cross-sectional study among patients tested for cancer susceptibility and thrombophilia

We evaluated whether genetic tests with evidence of clinical and personal utility (i.e. APC and BRCA1/2 tests) are associated with higher satisfaction and a more positive perception of care experience than those with undefined utility (i.e. tests for thrombophilia). A cross-sectional survey was performed through telephone interviews to patients tested for deleterious variants in APC or BRCA1/2 genes, or for inherited thrombophilia (FV Leiden and/or FIIG20210A) during a 5-year period (2008-2012). Three aspects of patient experience were assessed: effective communication through pre- and post-test genetic counselling; collaboration between caregivers on the management of patient care; and impact of genetic testing on quality of life. Overall 237 patients had telephone interviews. Multivariate logistic regression analyses showed that patients tested for APC or BRCA1/2 variants were more likely to be satisfied with both pre- and post-test counselling than those tested for inherited thrombophilia (APC vs. thrombophilia, p = 0.039 and 0.005; BRCA1/2 vs. thrombophilia, p = 0.030 and <0.001). Patients tested for APC were more likely to report an improvement in quality of life than those for thrombophilia (OR = 2.97, 95%CI 1.14, 7.72; p = 0.025). A positive association was observed between patients who underwent BRCA1/2 testing, and self-perceived improvement in quality of life (OR = 1.41, 95%CI 0.74, 2.69; p = 0.294). Tests of undefined clinical and personal utility are associated with a lower degree of patient satisfaction with genetic counselling and no clear opinions on changes in quality of life compared with those with well-defined utility.

Patterns and Appropriateness of Thrombophilia Testing in an Academic Medical Center

BACKGROUND

Clinical guidelines recommend against routine use of thrombophilia testing in patients with acute thromboembolism. Thrombophilia testing rarely changes acute management of a thrombotic event.

OBJECTIVE

To determine appropriateness of thrombophilia testing in a teaching hospital.

DESIGN

Retrospective cohort study.

SETTING

One academic medical center in Utah.

PARTICIPANTS

All patients who received thrombophilia testing between July 1, 2014, and December 31, 2014.

MAIN MEASUREMENTS

Proportion of thrombophilia tests occurring in situations associated with minimal clinical utility, defined as tests meeting at least 1 of the following criteria: discharged before results available; test type not recommended; testing in situations associated with decreased accuracy; duplicate testing; and testing following a provoked thrombotic event.

RESULTS

Overall, 163 patients received a total of 1451 thrombophilia tests for stroke (50% of tests; 35% of patients), venous thromboembolism (21% of tests; 21% of patients), and pregnancy-related conditions (15% of tests; 25% of patients). Of the 39 different test types performed, the most common were cardiolipin IgG and IgM antibodies (9% each), lupus anticoagulant (9%), and ß2-glycoprotein 1 IgG and IgM antibodies (8% each). In total, 911 tests (63%) were performed in situations associated with minimal clinical utility, with 126 patients (77%) receiving at least one such test. Only 2 patients (1%) had clear documentation of being offered genetic consultation.

CONCLUSIONS

Thrombophilia testing in this single-center study was often associated with minimal clinical utility. Strategies to improve testing practices (eg, hematology specialty consult prior to inpatient testing, improved order panels) might help minimize inappropriate testing and promote value-driven care.

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.

Clinical adherence to thrombophilia screening guidelines at a major tertiary care hospital

Essentials Thrombophilia screening has significantly increased but has limited clinical utility. We evaluated the positive rate of thrombophilia screening and adherence to published guidelines. Both the positive rate for thrombophilia screening and the adherence to guidelines were low. Guidance implementation is essential to improve current thrombophilia screening practice.

SUMMARY

Background Thrombophilia screening is widely performed but provides limited clinical utility in managing patients predisposed to venous thromboembolism. Although guidelines to limit testing have been published, adherence to those guidelines in the outpatient clinical setting has not been assessed. Objective To evaluate outpatient thrombophilia screening practices at a tertiary academic medical center. Methods We performed a retrospective review of the electronic medical records and a computational analysis of thrombophilia tests collected during a 3-year period (August 2010 to June 2013) at a large teaching hospital. Our primary outcome measures were positive diagnostic yield for thrombophilia and clinician adherence to published thrombophilia screening guidelines in the outpatient setting. Results and Conclusions We found a positive diagnostic yield of 13.8% (95% confidence interval 12.3% to 15.3%) for outpatient thrombophilia screening at our institution. Of the screening tests requiring a second confirmatory assay for definitive diagnosis, only 12% (95% confidence interval 10.3% to 13.7%) were appropriately obtained. We also observed that 73% of patients in our electronic medical record review were inappropriately tested based on existing screening guideline criteria. When parsed by specialty, we identified that hematologists had a higher adherence rate to guideline criteria than do physicians from other specialties. Our study confirms low adherence to thrombophilia screening guidelines across disciplines and indicates the need for continued clinician education.

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.

Pathogenesis of vascular complications in Cushing's syndrome

Chronic exposure to high glucocorticoid levels in Cushing's syndrome (CS) is often associated with alterations in the hemostatic system and the expression of prothrombotic phenotypes. Increased frequency of both atherothrombotic and venous thromboembolic events (VTE) has been reported in patients with CS. In general, cardiovascular complications in these patients cause a five-fold increase in mortality compared to the normal population. Although numerous abnormalities in the hemostatic system have been detected in patients with CS, the underlying mechanisms of the prothrombotic state are not fully elucidated. High levels of factor VIII and von Willebrand factor, with evidence of enhanced thrombin generation and decreased fibrinolytic activity, have been documented in several studies. However, it is not clear to what extent these changes contribute to the shift of hemostatic balance towards the hypercoagulable state and expression of thrombophilic phenotypes. Thrombosis is usually a multicausal disease, and all three components of the so-called Virchow triad, namely 1) vascular abnormalities and endothelial dysfunction, 2) hypercoagulability and 3) stasis, may play a variable role in the pathogenesis of the prothrombotic state in CS patients. Larger studies are needed to establish strategies for prevention of cardiovascular complications in patients with Cushing's syndrome.

Thrombophilia risk factors are associated with intrauterine foetal death and pregnancy-related venous thromboembolism

Pregnancy in healthy women is accompanied by hypercoagulable changes that may interact with thrombophilia risk factors and threaten pregnancy. However, the literature on this issue is conflicting. In investigating the relationship between pregnancy-associated complications and the presence of thrombophilia risk factors, we studied the records of 414 women who had been examined for inherited and acquired thrombophilia in the period 1996 to 2006 because of pregnancy-associated complications. Of a total of 885 pregnancies among the women, 397 were recorded as foetal loss/intrauterine foetal death during the first (62 %), second (25 %) or third trimester (13 %). One-hundred-and-two (25 %) women had had a thromboembolic event during one of their pregnancies, and 98 (24 %) had had pre-eclampsia on at least one occasion. Intrauterine growth restriction was found in 105 (25 %) of the women, and 29 (7 %) suffered placental abruption. We found that 120 (29 %) women had at least one thrombophilia risk factor. Factor V Leiden heterozygosity was the most common thrombophilia factor (n = 52), mostly linked with the risk of venous thromboembolism during pregnancy or postpartum and to foetal death during the second or third trimester. Fifty-three (13 %) women had antiphospholipid antibodies (lupus anticoagulant and/or anti-beta2-glycoprotein 1 antibodies) mainly associated with the risk of spontaneous abortion during the first trimester. In conclusion, thrombophilia was found to be considerably more common in women with pregnancy-associated complications in comparison with the general population, and most frequently in conjunction with venous thromboembolism during pregnancy and the postpartum period.

Testing for hereditary thrombophilia: a retrospective analysis of testing referred to a national laboratory

Background

Predisposition to venous thrombosis may be assessed through testing for defects and/or deficiencies of a number of hereditary factors. There is potential for confusion about which of these tests are appropriate in which settings. At least one set of recommendations has been published to guide such testing, but it is unclear how widely these have been disseminated.

Methods

We performed a retrospective analysis of laboratory orders and results at a national referral laboratory to gain insight into physicians' ordering practices, specifically comparing them against the ordering practices recommended by a 2002 College of American Pathologists (CAP) consensus conference on thrombophilia testing. Measurements included absolute and relative ordering volumes and positivity rates from approximately 200,000 thrombophilia tests performed from September 2005 through August 2006 at a national reference laboratory. Quality control data were used to estimate the proportion of samples that may have been affected by anticoagulant therapy. A sample of ordering laboratories was surveyed in order to assess potential measurement bias.

Results

Total antigen assays for protein C, protein S and antithrombin were ordered almost as frequently as functional assays for these analytes. The DNA test for factor V Leiden was ordered much more often than the corresponding functional assay. In addition, relative positivity rates coupled with elevations in prothrombin time (PT) in many of these patients suggest that these tests are often ordered in the setting of oral anticoagulant therapy.

Conclusion

In this real-world setting, testing for inherited thrombophilia is frequently at odds with the recommendations of the CAP consensus conference. There is a need for wider dissemination of concise thrombophilia testing guidelines.

Is screening for thrombophilia cost-effective?

PURPOSE OF REVIEW

The aim of this review was to examine the current evidence on the cost-effectiveness of screening for thrombophilia.

RECENT FINDINGS

Few studies have attempted to evaluate the cost-effectiveness of screening for thrombophilia. The direct medical costs associated with screening, in order to detect one case of thrombophilia and indeed to prevent a subsequent venous thromboembolism, are high. Irrespective of patient groups, selective history-based thrombophilia screening has been shown to be more cost-effective than universal or unselected population screening. When comparing across the high-risk patient groups, screening women prior to prescribing combined oral contraceptives was the least cost-effective strategy.

SUMMARY

Although thrombophilia is associated with a substantial increase in relative risk of venous thromboembolism, the absolute risk and the absolute numbers of expected events, and the subsequent estimated number of prevented events remain low. Based on existing evidence, screening for thrombophilia is unlikely to be cost-effective. However, the potential cost-effectiveness of thrombophilia screening may be improved if the screening strategies were to be refined through more accurate assessment of personal or family history of venous thromboembolism or the introduction of a more global coagulation test for screening.