Table 2.

Definitions of medium-high aPL titres, and of high-risk and low-risk aPL profile [7]

Medium-high aPL titres • aCL of IgG and/or IgM isotype in serum or plasma present in titres > 40 IgG phospholipid units or > 40 IgM phospholipid units, or > the 99th percentile, measured by a standardised ELISA. anti-β2GPI of IgG and/or IgM isotype in serum or plasma in titre > 99th percentile, messured by standardised ELISA.

High-risk aPL profile • The presence (in 2 or more occasions at least 12 weeks apart) of LA (measured according to ISTH guidelines), or of double (any combination of LA, aCL, or anti-β2GPI) or triple (all three subtypes) aPL positivity, or the presence of persistently high aPL titres.

Low-risk aPL profile • Isolated aCL or anti-β2GPI at low-medium titres, particularly if transiently positive.