Abstract
Functional tests for lupus anticoagulants (LA) as part of a thrombophilia workup are commonly performed in patients under anticoagulant therapy that may interfere with assay results. There is no consensus on how these tests should be assessed in patients on direct oral anticoagulants (DOACs). In this retrospective cohort study, we analysed data from patients with a history of thrombosis in whom dilute Russell viper venom time (dRVVT), LA-sensitive aPTT, and solid phase assays for antiphospholipid antibodies (aPL) were performed (n = 3,147, thereof 588 on rivaroxaban, 144 on apixaban, 1,179 on other anticoagulant drugs). The dRVVT ratio was correlated with rivaroxaban (r = 0.30, P < 10–4) but not with apixaban plasma levels. The LA-sensitive aPTT/aPTT ratio showed no correlation with DOAC levels. Correspondingly, the rate of patients with abnormal dRVVT test was significantly higher (P < 10–4) under rivaroxaban (88%) than in thrombosis patients without anticoagulant medication (6%), independent from their aPL plasma levels. No isolated positive results of functional LA testing in patients on anticoagulants could be confirmed in repeated testing after discontinuation of the medication (n = 40). These data indicate that rivaroxaban should be discontinued before functional LA testing is performed. However, viable interpretation of these tests appears to be less affected in patients on apixaban.
Highlights
Functional tests for lupus anticoagulants (LA) as part of a thrombophilia workup are commonly performed in patients under anticoagulant therapy that may interfere with assay results
Among the different anticoagulant drugs used in this study population were all drugs or drug classes currently indicated for treatment or prophylaxis of venous thromboembolism (VTE)
Only rivaroxaban, apixaban, low molecular weight heparin (LMWH) and vitamin K antagonists (VKA) were used in sufficiently large subpopulations to allow a reliable statistical analysis
Summary
Functional tests for lupus anticoagulants (LA) as part of a thrombophilia workup are commonly performed in patients under anticoagulant therapy that may interfere with assay results. There is no consensus on how these tests should be assessed in patients on direct oral anticoagulants (DOACs) In this retrospective cohort study, we analysed data from patients with a history of thrombosis in whom dilute Russell viper venom time (dRVVT), LA-sensitive aPTT, and solid phase assays for antiphospholipid antibodies (aPL) were performed (n = 3,147, thereof 588 on rivaroxaban, 144 on apixaban, 1,179 on other anticoagulant drugs). No isolated positive results of functional LA testing in patients on anticoagulants could be confirmed in repeated testing after discontinuation of the medication (n = 40) These data indicate that rivaroxaban should be discontinued before functional LA testing is performed. According to the international consensus criteria the diagnosis of APS is based on the combined presence of defined clinical manifestations as well as the persistent detection of antibodies directed against phospholipids, so called antiphospholipid antibodies (aPL)[4,5]. With respect to the LA tests, there is no standardised reference method addressing the issue of quality control, and no available technique can detect all L A6
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