Prevalence of antiphospholipid antibodies in an Australian cohort of patients with unprovoked venous thromboembolism

Antiphospholipid antibodies in pulmonary embolism treated with direct oral anticoagulants: Prevalence data from unselected consecutive patients

Background

Direct oral anticoagulants (DOACs) are the first-choice treatment option for the prevention of the recurrence of venous thrombosis in patients with pulmonary embolism (PE); however, their effect in patients with antiphospholipid syndrome (APS) is challenged. Therefore, the prevalence of antiphospholipid autoantibodies in patients with PE is noteworthy.

Objectives

To determine the prevalence of unselected patients presenting with PE who meet the criteria for APS based on elevated levels of anticardiolipin (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibodies.

Methods

Consecutive patients with PE, in whom DOACs were primarily initiated, were tested for aCL and aβ2GPI. If the levels were elevated, the tests were repeated after 12 weeks for APS diagnosis. Laboratory results and patient characteristics were retrospectively collected from a laboratory information system and electronic patient journal entries over a 2-year period.

Results

The prevalence of APS based on consistently elevated levels of aCL or aβ2GPI was 3.7% (10 of 267 patients). Three patients were double positive. In 11 out of 21 patients (52%) with initially elevated values, the levels of the antibodies normalized after 12 weeks. The patient characteristics were largely similar in those with APS and those without APS; however, patients with APS tended to be older and more likely to receive antithrombotic treatment at the time of PE.

Conclusion

We found a relatively low prevalence of APS based on aCL or aβ2GPI. The high rate of normalized levels of the antibodies after 12 weeks reaffirms the need for repeated tests for APS diagnosis. Older patients more frequently met the criteria for APS. Determining the effectiveness of DOACs in non-triple-positive patients with APS following venous thromboembolism is important to further determine the feasibility of unselected tests in patients with PE.

Low prevalence of antiannexin A5 antibodies in unprovoked venous thrombosis

INTRODUCTION

The antiphospholipid syndrome (APS) is characterized by thrombosis or pregnancy morbidity, and the detection in the blood of at least one of three antiphospholipid antibodies (lupus anticoagulant, or anticardiolipin or anti-β₂ -glycoprotein I antibodies). Diagnosing APS is important so that secondary prophylaxis may be administered to reduce risk of recurrent thrombosis and/or pregnancy morbidity. In addition to APS-defining antibodies, there may be additional autoantibodies that have a role in thrombosis and/or pregnancy morbidity. Furthermore, some patients have clinical manifestations highly suggestive of APS but are persistently negative for the APS-defining antibodies ("seronegative APS") and instead, have other autoantibodies. Antiannexin A5 (aANXA5) autoantibodies have been associated with increased risk of thrombosis and pregnancy morbidity; levels are also reportedly higher in patients with venous thrombosis compared with healthy controls. The prevalence of aANXA5 among patients with unprovoked venous thrombosis is not well-documented and determination of the frequency of aANXA5 is the objective of this study.

METHODS

We analysed sera from 148 patients with unprovoked venous thrombosis who had undergone routine laboratory testing for the present APS-defining antibodies.

RESULTS

aANXA5 IgG and IgM were present in 6% and 1%, respectively.

CONCLUSION

Prevalence of these antibodies in unprovoked venous thrombosis is comparable with frequencies reported in healthy individuals and is far lower than the prevalence in women with pregnancy morbidity. This may indicate lack of association with venous thrombosis, however, adequately powered case-control studies will be required to resolve this and prevalence data from this study will assist in the design of such studies.

Pulmonary embolism: update on management and controversies

Pulmonary embolism is a common and potentially fatal cardiovascular disorder that must be promptly diagnosed and treated. The diagnosis, risk assessment, and management of pulmonary embolism have evolved with a better understanding of efficient use of diagnostic and therapeutic options. The use of either clinical probability adjusted or age adjusted D-dimer interpretation has led to a reduction in diagnostic imaging to exclude pulmonary embolism. Direct oral anticoagulation therapies are safe, effective, and convenient treatments for most patients with acute venous thromboembolism, with a lower risk of bleeding than vitamin K antagonists. These oral therapeutic options have opened up opportunities for safe outpatient management of pulmonary embolism in selected patients. Recent clinical trials exploring the use of systemic thrombolysis in intermediate to high risk pulmonary embolism suggest that this therapy should be reserved for patients with evidence of hemodynamic compromise. The role of low dose systemic or catheter directed thrombolysis in other patient subgroups is uncertain. After a diagnosis of pulmonary embolism, all patients should be assessed for risk of recurrent venous thromboembolism to guide duration of anticoagulation. Patients with a venous thromboembolism associated with a strong, transient, provoking risk factor can safely discontinue anticoagulation after three months of treatment. Patients with an ongoing strong risk factor, such as cancer, or unprovoked events are at increased risk of recurrent events and should be considered for extended treatment. The use of a risk prediction score can help to identify patients with unprovoked venous thromboembolism who can benefit from extended duration therapy. Despite major advances in the management of pulmonary embolism, up to half of patients report chronic functional limitations. Such patients should be screened for chronic thromboembolic pulmonary hypertension, but only a small proportion will have this as the explanation of their symptoms. In the remaining patients, future studies are needed to understand the pathophysiology and explore interventions to improve quality of life.

Prevalence of confirmed antiphospholipid syndrome in 18-50 years unselected patients with first unprovoked venous thromboembolism

BACKGROUND

Antiphospholipid syndrome (APS) is an acquired thrombophilia disorder with prevalence not completely known in patients with first unprovoked venous thromboembolic events (VTE). Recent data suggest that the management of some APS patients should be different from that of patients with other thrombophilia. Our aim was to estimate the prevalence of APS in a community-based cohort of patients with a first unprovoked VTE.

METHODS

We conducted a cross-sectional study analyzing data from our computer assisted oral anticoagulant dosage program. Data of all consecutive patients aged 18 to 50 years who were seen between January 1, 2002 and December 31, 2011 for a first proximal unprovoked VTE were extracted. The prevalence and main features of patients who fulfilled the Sapporo revised criteria for APS were collected.

RESULTS AND DISCUSSION

A total of 524 incident patients aged 18 to 50 years were included in the anticoagulation clinic during the study period. Of them, 491 were tested for APS and 44 (9.0%; 95% confidence interval [CI]: 6.7-11.8) fulfilled APS criteria. Of 26 APS women, 8 (30.8%) were on combined oral contraceptive pill at the time of VTE, versus 108 (55.1%) in non-APS women (P = .02). No difference was observed between APS and non-APS patients in terms of gender or type of VTE. The prevalence of APS is high in young patients with a first unprovoked VTE. In the direct oral anticoagulant era, when and how to test for APS is challenging and deserves further investigation.