[Detection of lupus anticoagulant using a modified diluted Russell's viper venom time test]

Lupus anticoagulants (LA) are considered to be a significant risk factor in patients with unexplained thrombosis and are often present in women who have recurrent miscarriages. According to Petri et al, LA detectable using a diluted Russell's Viper Venom time (dRVVT) test are more closely linked with thrombosis in patients with systemic lupus erythematosus than are anticardiolipin antibodies. We evaluated a new simplified dRVVT test, that is, a combination of LUPO-TESTII and LUCOR, and found that the ratio of LUPO-TESTII/LUCOR values is a good indicator for detection of LA. The cut-off point of the ratio based on receiver-operating characteristic (ROC) analysis was set at 1.07. The sensitivity and specificity were 92.3% and 96.8%, respectively. The ratio of LUPO-TESTII/LUCOR values of 24 (92.3%) of 26 LA-positive patients was significantly higher than those of warfarin-treated patients, patients with hereditary clotting-factor deficiency and patients positive for specific clotting-factor inhibitors (p < 0.01). It was shown that the result was not influenced by warfarin and/or heparin treatment and the presence of specific clotting-factor inhibitors. The ratio of LUPO-TESTII/LUCOR values is regarded as a more useful indicator for the detection of LA than the platelet neutralization procedure test.