Diagnostic Criteria for Catastrophic Antiphospholipid Syndrome (CAPS)

The Catastrophic Antiphospholipid Syndrome (CAPS) is a rare life-threatening form of Antiphospholipid Syndrome (APS) in which widespread intravascular thrombosis results in multiorgan ischemia and failure. CAPS is the initial presentation of APS in nearly half of patients, while the remaining half has a history of APS.

Diagnostic criteria for CAPS are: 1) involvement of three or more organs/tissues; 2) development of manifestations in less than a week; 3) histological evidence of intravascular thrombosis; and 4) presence of antiphospholipid antibodies on two occasions six weeks apart. A definite diagnosis of CAPS is made when all four diagnostic criteria are present. The diagnosis of CAPS is probable when a combination of these criteria is present.

Diagnostic Criteria for CAPS
1) Involvement of three or more organs/tissues*
2) Development of manifestations in less than a week
3) Histological evidence of intravascular thrombosis**
4) Presence of antiphospholipid antibodies on two occasions six weeks apart***

Definite CAPS:
– All four criteria
Probable CAPS:
– All four criteria, except for only two organs, systems, and/or tissues involved
– All four criteria, except for the absence of laboratory confirmation owing to the early death of a patient never tested for antiphospholipid antibodies before the CAPS
– Criteria (1), (2), and (4)
– Criteria (1), (3), and (4) and the development of a third event between one week and one month after presentation, despite anticoagulation

Given that many times biopsy and histological confirmation of small vessel occlusion cannot be obtained due to the critical condition of the patients, a proposal has been made to substitute the “histopathology criteria” by the exclusion of other diagnoses.

* 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 h).
** 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 12 weeks apart (not necessarily at the time of the event), according to the proposed preliminary criteria for the classification of definite APS.



  1. Nayer A, Ortega LM. Catastrophic antiphospholipid syndrome: a clinical review. J Nephropathol. 2014 Jan;3(1):9-17 [Medline]
  2. Cervera R, Rodríguez-Pintó I, Espinosa G. The diagnosis and clinical management of the catastrophic antiphospholipid syndrome: A comprehensive review. J Autoimmun. 2018 Aug;92:1-11. [Medline]
  3. Rodríguez-Pintó I, Moitinho M, Santacreu I, Shoenfeld Y, Erkan D, Espinosa G, Cervera R; CAPS Registry Project Group (European Forum on Antiphospholipid Antibodies). Catastrophic antiphospholipid syndrome (CAPS): Descriptive analysis of 500 patients from the International CAPS Registry. Autoimmun Rev. 2016 Dec;15(12):1120-1124. [Medline]

Created Sep 4, 2018.