Background: Lupus anticoagulant (LA) is a set of heterogeneous auto-antibodies involved in thrombotic and obstetric events, notably in the context of antiphospholipid syndrome. For LA detection, two parallel methods are recommended, each combining a screening and a confirmatory test.

Objectives: To evaluate the performance of screening tests in terms of sensitivity and specificity to LA.

Methods: A retrospective and descriptive study was conducted, including requests for LA sent to our laboratory, between January 2022 and November 2024. LA testing was performed using two techniques: Diluted Russell Viper Venom Time (dRVVT) and Silica Coagulation Time (SCT). Preanalytical conditions were followed, particularly the absence of drug interference. Positive screening was defined by an SCT or dRVVT ratio > 1.2. The presence of ACC was defined by a normalized ratio >1.16 for SCT and >1.2 for dRVVT.

Results: A total of 247 specimen were studied. The sex ratio (F/M) was 2.63 and the mean age was 45.9 years, with extremes of 11 and 86 years. The requesting departments were dominated by internal medicine (80.6%), followed by gastroenterology (4.5%) and neurology (3.6%). Among the risk factors for thrombosis, systemic lupus erythematosus was noted in 13.2% of patients, and the presence of a personal history of thrombosis was observed in 11.7% of cases. LA testing was positive in 20.6% of patients (n=51) by dRVVT and in 9.7% (n=24) by SCT. At the screening phase by SCT, specificity was high at 95%, with sensitivity limited to 50%. By dRVVT, screening showed better sensitivity at 86.6% and specificity at 84.2%. A discordance between the two screening tests was observed in 23.3% of cases (n=60). Two groups were defined: for group 1 represented by 20.2% of patients (n=52), screening was positive by dRVVT and negative by SCT, and for group 2 estimated at 3.1% of cases (n=8), screening was positive by SCT and negative by dRVVT. Confirmation by normalized ratio in group 1 was positive in 50% of the cases (n=26) by dRVVT and in 8% of patients by SCT. In Group 2, confirmation by dRVVT was negative in all 8 patients and positive in 2 patients by SCT.

Conclusion: Our results support the need to carry out integrated tests from the outset as a biological decision criterion.

REFERENCES: NIL.

Acknowledgements: NIL.

Disclosure of Interests: None declared.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.