Laboratory Profile of Lupus Anticoagulant Positive Cases and its Association with Clinical Presentation- Experience from a Tertiary Care Centre in Southern India

Antiphospholipid syndrome (APS) is an autoimmune disease with specific clinical features and the presence of antiphospholipid antibodies (aPL) like anti-beta2 glycoprotein 1 (anti-β2gp1), anti-cardiolipin antibody (aCL), and/or lupus anticoagulant (LA). The purpose of this study was to evaluate the laboratory profile of LA-positive cases and study its association with various clinical presentations. In this ambispective analytical study over 20 months, LA-positive cases (n = 167) from among 970 cases screened were included. Tests for LA were integrated dilute Russell’s Viper venom time (dRVVT) and silica clotting time (SCT) using screen-confirm procedure with mixing whenever necessary. The clinical profile and other investigations like aCL and anti-β2gp1were noted from records. The sensitivity of dRVVT and SCT for LA positivity were 78.4% and 79.4%, respectively. Based on the clinical presentation the cases were grouped as abortion, thrombosis, systemic lupus erythematosus (SLE) and others. The thrombotic group showed significantly higher (94%) dRVVT positivity, with an odds ratio of 5.56 (95% CI: 1.61 to 19.15). SCT, aCL, or anti-β2gp1 positivity did not show any significant risk association with thrombosis or abortion. SLE- group showed more frequent dual-LA (dRVVT and SCT) positivity. All groups showed higher anti-β2gp1 positivity than aCL. Persistent LA positivity after 12-weeks was more frequent with dual-LA positive (91.67%), double (LA + aCL/anti-β2gp1) and triple (LA + aCL + anti-β2gp1) positive cases (100%). Both dRVVT and SCT had comparable sensitivity. dRVVT positivity was significantly associated with increased thrombotic risk. Persistent LA positivity was more often seen with initially dual, double or triple LA positive cases.