Frequent False‐positive results of lupus anticoagulant tests in plasmas of patients receiving the new oral anticoagulants and enoxaparin

Abstract

Dabigatran etexilate, RIV, and enoxaparin affect tests for LA not only in screening and mixing, but also in confirmatory studies. We considered that LA testing should not to be performed when patients are taken these drugs, particularly if blood is collected at peak, in order to avoid false-positive results.

Dilute Russell’s viper venom time reagents in lupus anticoagulant testing: a well-considered choice

“…False positivity in RIV-treated patients was illustrated previously [21][22][23][24]. Martinuzzo et al found that most RIV-treated patients presented prolonged dRVVT screen results without correction with PNP and mostly LAC ratios above the CO [21].…”

“…So far, only the CLSI guidelines briefly mention the risk of false-positive LAC interpretations in dabigatran (DAB)-and rivaroxaban (RIV)-treated patients [4]. Although several reports exist on the false-positivity in LAC testing by DOAC [19][20][21][22][23][24], susceptibility of specific reagents has not been investigated yet.…”

Lupus anticoagulant mixing tests for multiple reagents are more sensitive if interpreted with a mixing test‐specific cut‐off than index of circulating anticoagulant

“…For samples from patients with no other causes of clotting time prolongation and LA assay confirmatory test results within reference intervals, the increasingly popular paradigm of integrated testing is sufficient to detect the presence of LA without performing the mixing test at all 6, 7, 8, 9, 26, 27, 28, 31, 33, 34. However, in situations where alternative or co‐existing coagulation abnormalities are present, mixing tests can improve specificity of LA testing 34, 35, 36, 37. While some authors contend that LA can be detected with integrated testing alone, even in situations such as anticoagulant therapy,31, 36 other studies have evidenced improved diagnostic accuracy where initial analysis is not clear cut 34, 38.…”

Monitoring target-specific oral anticoagulants

“…Therefore, these assays, for example, measures of antithrombin, protein C, or protein S activity, APC resistance, and lupus anticoagulant testing, should not be performed in patients on these drugs. 23,[32][33][34] False-positive testing for lupus anticoagulants, even with a positive phospholipid correction step, have been reported in patients on each of these drugs. 34 Measures of antigen levels or DNA-based assays will not be affected by these drugs.…”