Classification Criteria for APS

Abstract

An international consensus statement on classification criteria for definite APS was published in 1999. A patient with APS must meet at least one of the two clinical criteria (vascular thrombosis or pregnancy complications) and at least one of the two laboratory criteria (aCL and/or LA). Although these criteria have been shown to be specific and sensitive for the classification of primary and secondary APS, the absence of “major” or “essential” features in the presence of “minor” features should not discourage the clinician from making the diagnosis when other causes of such features have been ruled out, since other well-recognized features of APS such as thrombocytopenia, hemolytic anemia, transient ischemic attacks, transverse myelitis, livedo reticularis, valvular heart disease, demyelinating syndromes, chorea, and migraine were not thought to have as strong an association as the final criteria and were excluded as classification criteria. These criteria have been revised in 2006 to include anti-β2GPI as a laboratory criterion for APS, and laboratories around the world are being encouraged to standardize their methodology for the detection of these antibodies (Table 4.1).