Clinical and laboratory practice for lupus anticoagulant testing: An International Society of Thrombosis and Haemostasis Scientific and Standardization Committee survey

Background Current guidelines have contributed to more uniformity in the performance and interpretation of lupus anticoagulant (LA) testing. However, points to reconsider include testing for LA in patients on anticoagulation, cut-off values, and interpretation of results. Objectives The aim of this International Society of Thrombosis and Haemostasis Scientific and Standardization committee (ISTH SSC) questionnaire was to capture the spectrum of clinical and laboratory practice in LA detection, focusing on variability in practice, so that the responses could inform further ISTH SSC recommendations. Methods Members of the ISTH SSC on Lupus Anticoagulant/Antiphospholipid Antibodies and participants of the Lupus Anticoagulant/Antiphospholipid Antibodies Programme of the External quality Control of diagnostic Assays and Tests Foundation were invited to complete a questionnaire on LA testing that was placed on the ISTH website using RedCap, with data tallied using simple descriptive statistics. Results There was good agreement on several key recommendations in the ISTH and other guidelines on LA testing, such as sample processing, principles of testing, choice of tests, repeat testing to confirm persistent positivity and the use of interpretative reporting. However, the results highlight that there is less agreement on some other aspects, including the timing of testing in relation to thrombosis or pregnancy, testing in patients on anticoagulation, cut-off values, and calculation and interpretation of results. Conclusions Although some of the variability in practice in LA testing reflects the lack of substantive data to underpin evidence-based recommendations, a more uniform approach, based on further guidance, should reduce the inter-center variability of LA testing.