Predictive power of aPLs in APS diagnosis
The diagnostic power of aPLs positivity (>18 U/ml) was evaluated for sensitivity, specificity, accuracy, Youden Index, PPV, NPV, and ORs in APS diagnosis from HC group in table 2. For IgA, the sensitivity and accuracy of the combination of aCL IgG, IgM, or IgA were significantly higher than that of aCL IgG or IgM (p<0.001), while specificity was lower (p=0.031). A similar result was observed for aCL or aB2GpI IgG or IgM or IgA compared to aCL or aB2GpI IgG or IgM. As for aAnxV, the sensitivity and accuracy of aAnxV IgG or IgM was significantly higher than that of aB2GpI IgG or IgM (P<0.001). In addition, a combination of aCL, aβ2GpI, or aAnxV IgG or IgM had significantly higher sensitivity (p=0.016) compared to that of aCL or aβ2GpI IgG or IgM.
As illustrated in figure 1, ROC curves were applied to evaluate the predictive value of aPLs or their combined positivity. Among individual aPLs, aβ2GP1 IgG (0.915), aCL IgA (0.853), aCL IgM (0.767), and aAnxV IgG (0.728) had the largest AUC values. Adding IgA, aAnxV or aPS/PT IgG or IgM to aCL or aβ2GpI IgG or IgM would both increase AUC (0.927, 0.951, and 0.936 compared to 0.925).