[Research of the efficiency of different lupus anticoagulant assays]

To provide valuable test by evaluating the efficiency of lupus anticoagulant assays based on different principles.

370 citrated samples were recruited, LA were tested by dRVVT, SCT, APTT-Actin, APTT-Actin FSL and APTT-SS respectively, and 1:1 mixing tests before incubation were studied in all the recruited subjects. For LA testing, the results of 1:1 mixing test were expressed as index of circulating anticoagulant (ICA), and the confirm test results were expressed as percent of correction (C) and normalized ratio (NR). The reference interval (RI)/Cut-off values of all the assays were established, and the efficiency of all the assays were further studied.

The RI/Cut-off values of all assays were different. The sensitivity of dRVVT were the highest among all the assays (70.3%-93.1%), and the sensitivity of APTT (<55.0%) were the lowest. The sensitivity of APTT-SS (47.5%-53.5%) were higher than APTT-Actin (32.7%-39.6%) and APTT-Actin FSL (29.7%-36.6%). The specificity of dRVVT, SCT and three APTT were 91%-100%, 80.6%-100%, and 85.1%-98.5%, respectively. The specificity of SCT confirm test were 100%. Sensitivity of all the five methods were decreased in the weak positive LA. The sensitivity of dRVVT and SCT were more than 50.0%, however, the sensitivity of APTT-Actin and APTT-Acitn FSL were less than 16.0%. The sensitivity of APTT-SS were 23.7%-30.5%. Except the APTT-SS, dRVVT and SCT were correlated with thrombotic risk in APS patients (OR: 5.562-9.240, P<0.05).

Every Laboratory should establish local LA RI/Cut-off values. dRVVT is the best assay for LA test, and APTT-SS method is superior to the other APTT method. The different test combinations of dRVVT and SCT are correlated with thrombotic risk in APS patients.