Ordering Patterns of Thrombophilia Testing and Its Appropriateness

Background Despite society recommendations to limit thrombophilia testing, this testing is often sent inappropriately. The results of thrombophilia testing frequently do not affect management. Additionally, interpretation of thrombophilia testing is confounded by acute thrombosis, anticoagulation (AC) therapy, and other medical comorbidities. Incorrect test selection is also a source of unnecessary testing [i.e. Factor V (FV) activity level instead of Factor V Leiden (FVL)]. The aim of our study was to assess ordering patterns for thrombophilia testing by qualifying the number of tests, identifying the requesting services, and assessing the appropriateness of testing. Methods This was a retrospective study of thrombophilia testing performed at LAC+USC Medical Center, Los Angeles, CA from January 1, 2019 to December 31, 2019. A laboratory query of thrombophilia testing was performed to identify eligible adult patients who received thrombophilia testing without a prior confirmed thrombophilia. Thrombophilia testing included: FVL and prothrombin 20210 gene mutations; activated protein C (APC) resistance; antithrombin, or protein C or S activity levels; and antiphospholipid syndrome (APS) evaluation with lupus anticoagulant, cardiolipin (CL) immunoglobulins IgM/G, and beta-2 glycoprotein (b2gp) IgM/IgG; and JAK2 V617F mutation. Homocysteine (HC) levels and methylenetetrahydrofolate reductase (MTHFR) gene mutation testing were considered to have limited clinical utility. FV activity and phosphatidylserine IgM/IgG were considered incorrect tests. The electronic medical record was reviewed for clinical history, indication for testing, requesting service, and appropriateness. The criteria for defining appropriateness were determined based on major society guidelines and literature review. The main criteria are summarized here. Testing was considered inappropriate for a provoked venous thromboembolism (VTE) or stroke/transient ischemic attack (TIA). For unprovoked VTE, testing was considered inappropriate for patients > 45 yo except for APS testing. For non-stroke arterial thrombosis, recurrent pregnancy loss or stillbirth, and diagnostic evaluation of suspected lupus, APS testing only was considered appropriate. Results 450 patients underwent thrombophilia testing with a mean age of 42 (range: 18-90); 76% were female and 81% were Hispanic. A total of 1698 thrombophilia tests were sent by 27 services. Testing was done in the following settings: inpatient (40%), outpatient (59%), and emergency department (1%). The mean tests per patient were 3.7 (range: 1-12). The most common requesting services were rheumatology (24%), obstetrics-gynecology (19%), and internal medicine/medicine-pediatrics (14%). Hematology requested 10% of tests. Common indications for testing were VTE (21%), rheumatology-related (25%), pregnancy-related (13%), ischemic stroke/TIA (9%), ocular-related (7%), non-stroke arterial thrombosis (3%), and dermatology-related (4%) (Table 1). 5% (84 tests) were sent for the evaluation of other non-thrombotic conditions. 8% (132 tests) were sent for > 1 indication, such as concurrent arterial and venous events. 840 tests (49%) were deemed inappropriate. Common reasons for inappropriate testing included provoked VTE events, stroke/TIA, APS testing after first pregnancy loss, current AC, and duplicate testing (Table 2). APS testing issues included testing for LAC while on AC, incomplete testing (both CL and b2GP not sent), incorrect tests (phosphatidylserine IgM/IgG), and repeat testing < 12 weeks from prior. Incorrect/redundant testing for FVL included: FV activity levels (36 total tests; 9 ordered in additional to FVL and 27 ordered instead of FVL) and APC resistance ordered simultaneously with FVL in 7 patients. Of note, 92 tests were sent for evaluation of non-thrombotic conditions. Conclusions Thrombophilia testing is often done inappropriately. Correct test selection is also a relatively common issue, particularly with APS and FVL testing. Given the large number of services ordering thrombophilia testing at our training hospital and this testing being sent for a variety of reasons, it is unlikely that physician education alone will lead to a substantial or sustained decrease in the number of inappropriate tests. Rather, it may be necessary to restrict at least some thrombophilia testing to certain services. Figure 1 Figure 1. Disclosures Piatek: Rigel: Consultancy, Research Funding; Alexion: Consultancy, Research Funding; Apellis: Research Funding; Dova: Consultancy, Speakers Bureau.

Acquired and Inherited Thrombophilia Testing in Patients with Chronic Thromboembolic Pulmonary Hypertension: Value of Testing in an Academic Health Center

Introduction Chronic thromboembolic pulmonary hypertension (CTEPH) is classed as group 4 in the present classification of pulmonary hypertension. The pathophysiology of CTEPH is complex, mainly is a consequence of prior acute pulmonary embolism with failure of thrombi to resolve and the recent recognition of added small vessel changes which impacts long-term outcomes even after surgical management. The role of thrombophilia testing in this condition has been debated. Hence, we here analyzed the utility of thrombophilia testing in CTEPH from a center in a developing country. Methods This is a single institution (Narayana Health City, Bangalore); retrospective study including patients ≥ 18 years of age who underwent thrombophilia workup in a diagnosis of CTEPH from January 2019 till July 2021. Tests done to evaluate thrombophilia included factor V Leiden; prothrombin F20210A mutation; MTHFR gene mutation; Protein C, S, and antithrombin deficiency; lupus anticoagulant, anti-beta2 glycoprotein I (IgM and IgG) and anticardiolipin antibody (IgM and IgG); hyperhomocysteinemia and anti-nuclear antibody testing (ANA-IF). The study was approved by the ethics committee of the institute and was carried out in accordance with the principles of the declaration of Helsinki. Results and discussion The study included 56 patients with a median age of 37 years (range 23-50), and 36 (64%) were males. Patients with recurrent venous thrombosis included 37 (66%), with the majority having thrombosis at 2 sites (53%; 22 patients with associated deep vein thrombosis). A family history of thrombosis was present in 4 patients. The majority of patients received vitamin K antagonists (76%), with the rest receiving direct oral anticoagulants (DOAC). Among the tests sent for acquired thrombophilia, ANA-IF and antiphospholipid antibody (APLA) were most frequently evaluated (94%). ANA-IF and APLA tests were positive in 5.6% and 30.1%, respectively. Among the APLA tests, Anti-beta2 glycoprotein I (IgM or IgG) was the most commonly detected antibody (13/46), followed by anticardiolipin antibody (IgG or IgM) (9/43) and lupus anticoagulant (7/40). Double and triple positive APLA were present in 3 and 4 patients, respectively. Homocysteine levels were high in 93.7% though only 16 patients were tested in this cohort. Among the tests for inherited thrombophilia, genetic tests (factor V Leiden, prothrombin F20210A mutation, and MTHFR gene mutation) were tested in only ~50%. Twenty-three percent were positive for heterozygous MTHFR followed by MTHFR compound heterozygous (10%) and heterozygous factor V Leiden heterozygous (10%). Antithrombin III, protein C, and S were tested in ~30% of patients. Antithrombin III was low in only 1 patient, with protein C and S assays being normal in all the patients. The cost analysis was calculated, showed a median of $364 (₹ 27,055) was spent per person on thrombophilia workup. The median cost incurred per patient for inherited thrombophilia workup was $232 (₹ 17,300) and for acquired thrombophilia was $132 (₹ 9814), respectively. Conclusion This single-institution study on thrombophilia workup in CTEPH patients reveals that APLA was the most commonly performed test with high positivity rates of 30.1%. Among the inherited thrombophilia, the positivity rate of MTHFR mutation was highest (33.3%), with other tests having a low positivity rate (0-10%). Hence, we would recommend APLA testing in all patients with CTEPH considering its high positivity and clinical utility. Testing for other thrombophilias should be pursued judiciously especially in economically restrictive settings. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Evaluation of thrombophilia testing in the inpatient setting: A single institution retrospective review

Background Thrombophilia workup is typically inappropriate in the inpatient setting as testing may be skewed by anticoagulation, acute thrombosis, or acute illness. Objective To determine adherence of inpatient thrombophilia testing with institutional guidelines. Patients and methods A retrospective study to evaluate thrombophilia testing practices of adult patients who were admitted to Lehigh Valley Hospital at Cedar Crest with either venous thromboembolism or ischemic stroke in 2019. Testing included inherited and acquired thrombophilia. Patient charts were individually reviewed for three measured outcomes: 1) the number of appropriate thrombophilia testing in the inpatient setting; 2) the indications used for thrombophilia testing; 3) the proportion of positive thrombophilia tests with change in clinical management. Results 201 patients were included in our study. 26 patients (13%) were tested appropriately in accordance with institution guidelines and 175 (87%) patients were tested inappropriately. The most common reason for the inappropriate testing was testing during acute thrombosis. 28 of the 201 patients had positive thrombophilia tests, but the reviewers only noted 7 patients with change in clinical management—involving anticoagulation change. Conclusion Our study revealed that a majority of inpatient thrombophilia testing did not follow institutional guidelines for appropriate testing and did not change patient management. These thrombophilia tests are often overutilized and have minimal clinical utility in the inpatient setting.

A multi-laboratory assessment of congenital thrombophilia assays performed on the ACL Top 50 family for harmonisation of thrombophilia testing in a large laboratory network

Objectives Thrombophilia testing is commonly performed within hemostasis laboratories, and the ACL TOP 50 family of instruments represent a new ‘single platform’ of hemostasis instrumentation. The study objective was to evaluate these instruments and manufacturer reagents for utility of congenital thrombophilia assays. Methods Comparative evaluations of various congenital thrombophilia assays (protein C [PC], protein S [PS], antithrombin [AT], activated protein C resistance [APCR]) using newly installed ACL TOPs 550 and 750 as well as comparative assessments with existing, predominantly STAGO, instrumentation and reagents. Verification of manufacturer assay normal reference ranges (NRRs). Results HemosIL PC and free PS assays showed good comparability with existing Stago methods (R>0.9) and could be considered as verified as fit for purpose. HemosIL AT showed high relative bias with samples from patients on direct anti-Xa agents, compromising utility. Manufacturer NRRs for PC, PS and AT were verified with minor variance. Given the interference with direct anti-Xa agents, an alternate assay (Hyphen) was evaluated for AT, and the NRR also verified. The HemosIL Factor V Leiden (APC Resistance V) evidenced relatively poor performance compared to existing assays, and could not be adopted for use in our network. Conclusions This evaluation of HemosIL reagents on ACL TOP 50 Family instruments identified overall acceptable performance of only two (PC, free PS) of four thrombophilia assays, requiring use of third-party reagents on ACL instruments for the other two assays (AT, APCR).

Thrombophilia Testing After Ischemic Stroke

Thrombophilia testing is frequently performed after an ischemic stroke, particularly when cryptogenic. However, there is minimal evidence supporting a significant association between most conditions assessed through thrombophilia testing and ischemic stroke, and the rationale for thrombophilia testing in many clinical situations remains uncertain. In this topical review, we review and contextualize the existing data on the risks, predictors, and outcomes of thrombophilic conditions in patients with ischemic stroke. We report that inherited thrombophilias have an uncertain relationship with ischemic stroke. Conversely, antiphospholipid syndrome, an acquired immune-mediated thrombophilia, seems to be a strong risk factor for arterial thromboembolic events, including ischemic stroke, and especially among young patients. Our findings suggest that certain circumstances may warrant targeted thrombophilia testing, such as stroke in the young, cryptogenic stroke, and high estrogen states. Future prospective studies should investigate the utility and cost effectiveness of thrombophilia testing in various stroke settings, including among patients with patent foramen ovale; as well as the optimal secondary stroke prevention regimen in patients with confirmed thrombophilia, particularly if no other potential stroke mechanism is identified.

Influence of DOACs and DOAC Remove® on coagulation assays during thrombophilia testing in DOAC treated patients

Background/Aim. Direct oral anticoagulants (DOACs) administration has a significant interference on coagulation assays. Our study was conducted in order to evaluate the effect of DOACs and DOAC Remove? on coagulation assays during thrombophilia testing. Methods. In the period of January 2019 to the end of June 2020 30 DOAC treated patients tested for thrombophilia, due to venous thromboembolism (VTE), 14 females and 16 males aged 23 to 63 years (median age 47.6 years), were included in the study. Thrombophilia testing was performed using DOAC Remove? tablets (activated charcoal). The results before and after DOAC Remove? were compared. Results. Positive LA results were observed in 20% apixaban, 100% dabigatran, and 70% rivaroxaban treated patient, while in samples after DOAC Remove? the LA positivity was observed only in one from the apixaban group. Before DOAC Remove?, the APC-R ratio was measurable in 40% dabigatran, and 80% rivaroxaban treated patients, while, after using DOAC Remove? the APC-R was measurable in all cases. Comparing the results obtained from the samples before and after DOAC Remove?, a difference was noted in relation to all dRVVT tests, except for the dRVVT ratio in the apixaban group. Clot-based methods for detection of the APC resistance are significantly affected by dabigatran, and less by rivaroxaban. Conclusion. DOAC was practically inactivated after the addition of the DOAC Remove?, which made it possible to perform analyses for the LA and APC-R testing freely and obtain relevant results.