Table 4

 Preliminary criteria for the classification of catastrophic antiphospholipid syndrome4

*Usually clinical evidence of vessel occlusions, confirmed by imaging techniques when appropriate. Renal involvement is defined by a 50% rise in serum creatinine, severe systemic hypertension (>180/100 mm Hg). and/or proteinuria (>500 mg/24 hours).
†For histopathological confirmation, significant evidence of thrombosis must be present, although vasculitis may coexist occasionally.
‡If the patient had not previously been diagnosed as having an APS, the laboratory confirmation requires that the presence of antiphospholipid antibodies must be detected on two or more occasions at least six weeks apart (not necessarily at the time of the event), according to the proposed preliminary criteria for the classification of definite APS.
(1) Evidence of involvement of three or more organs, systems, and/or tissues*
(2) Development of manifestations simultaneously or in less than one week
(3) Confirmation by histopathology of small vessel occlusion in at least one organ or tissue†
(4) Laboratory confirmation of the presence of antiphospholipid antibodies (lupus anticoagulant and/or anticardiolipin antibodies)‡
Definite catastrophic APS: all four criteria
Probable catastrophic APS—any of the following:
(a) All four criteria, except for only two organs, systems, and/or tissues involved
(b) All four criteria, except for the absence of laboratory confirmation (within at least 6 weeks) owing to the early death of a patient never tested for aPL before the catastrophic APS
(c) Criteria (1), (2), and (4)
(d) Criteria (1), (3), and (4) and the development of a third event between one week and one month after presentation, despite anticoagulation