Lupus anticoagulant testing using two parallel methods detects additional cases and predicts persistent positivity

Background: Antiphospholipid antibody syndrome (APS) is characterized by laboratory evidence of antiphospholipid antibodies (aPL) [e.g. lupus anticoagulant (LA), anticardiolipin (ACL), and/or antiβ2-glycoprotein I (aB2GPI)] in a clinical setting of thrombosis or pregnancy morbidity. The International Society on Thrombosis and Haemostasis recommends two different testing modalities to detect LA. To evaluate these recommendations in a clinical setting, our hospital, a tertiary care center with a specialized coagulation laboratory, added the dilute Russell's viper venom time to be performed in parallel with the PTT-lupus anticoagulant to detect LA.

Methods: Results of aPL testing were collected on all patients who had LA testing for one year. Chart review was performed to correlate LA results with ACL, aB2GPI, and clinical history.

Results: Patients who were initially LA positive by both PTT-lupus anticoagulant and dilute Russell's viper venom time were more likely to be persistently positive. Patients who were positive for ACL and aB2GPI were likely to be positive by both LA methodologies. No single method was absolutely sensitive, as cases of APS were detected by PTTLA only, DRVVT only, and both methods.

Conclusions: The addition of a second testing method for LA provides additional diagnostic information and may be helpful in stratifying risk of thrombosis.