Diagnostic criteria

The first classification criteria ('Sapporo criteria') was developed in 1999 which suggested a diagnosis of APS in presence of one of both the classical clinical manifestations (thrombosis or pregnancy complication) and the persistent high-titre positivity of anti-cardiolipin antibodies (aCLs) or lupus anticoagulant (LAC) (1).

In 2006, the criteria were revised and published as the Sydney criteria where anitphospholipid syndrome is said to be present if at least one of the clinical criteria and one of the laboratory criteria below are met

Clinical criteria

• vascular thrombosis
  • one or more clinical episodes of arterial, venous or small vessel thrombosis
• morbidity in pregnancy
  • one or more unexplained deaths of a morphologically normal fetus at or beyond the 10th week of gestation
  • one or more pre-term births of a morphologically normal neonate before the 34th week of gestation because of: (i) eclampsia or severe pre-eclampsia or (ii) recognized features of placental insufficiency
  • three or more unexplained consecutive spontaneous miscarriages before the 10th week of gestation, with maternal anatomic or hormonal abnormalities and paternal and maternal chromosomal causes excluded

Laboratory criteria

• lupus anticoagulant (LA) present in plasma, on two or more occasions at least 12 weeks apart
• anticardiolipin (aCL) antibody of immunoglobulin (Ig)G and/or IgM isotype in serum or plasma, present in medium or high titre (i.e. >40GPL units or MPL units, or > the 99th centile), on two or more occasions, at least 12 weeks apart
• anti-b2-glycoprotein I antibody of IgG and/or IgM isotype in serum or plasma (in titre >the 99th centile), present on two or more occasions at least 12 weeks apart

Reference:

• (1) Taraborelli M, Andreoli L, Tincani A. Much more than thrombosis and pregnancy loss: the antiphospholipid syndrome as a 'systemicdisease'. Best Pract Res Clin Rheumatol. 2012;26(1):79-90.
• (2) Devreese K, Hoylaerts MF. Challenges in the diagnosis of the antiphospholipid syndrome. Clin Chem. 2010;56(6):930-40