Classification criteria for CAPS
| Criteria |
| 1. Evidence of involvement of ≥3 organs, systems, tissues, or a combination |
| 2. Development of manifestations simultaneously or in <1 week |
| 3. Confirmation by histopathology of small-vessel occlusion in at least 1 organ or tissue∗ |
| 4. Laboratory confirmation of the presence of aPL antibodies according to international criteria1 |
| Definite CAPS |
| All 4 aforementioned criteria |
| Probable CAPS |
| All 4 aforementioned criteria, except only 2 organs, systems, tissues, or a combination involved; or |
| All 4 aforementioned criteria, except for the absence of laboratory confirmation of antiphospholipid antibodies by repeat testing; or |
| Criteria 1, 2, and 4; or |
| Criteria 1, 3, and 4, with the development of a third event >1 week but within 1 month of presentation, despite anticoagulation |
| Criteria |
| 1. Evidence of involvement of ≥3 organs, systems, tissues, or a combination |
| 2. Development of manifestations simultaneously or in <1 week |
| 3. Confirmation by histopathology of small-vessel occlusion in at least 1 organ or tissue∗ |
| 4. Laboratory confirmation of the presence of aPL antibodies according to international criteria1 |
| Definite CAPS |
| All 4 aforementioned criteria |
| Probable CAPS |
| All 4 aforementioned criteria, except only 2 organs, systems, tissues, or a combination involved; or |
| All 4 aforementioned criteria, except for the absence of laboratory confirmation of antiphospholipid antibodies by repeat testing; or |
| Criteria 1, 2, and 4; or |
| Criteria 1, 3, and 4, with the development of a third event >1 week but within 1 month of presentation, despite anticoagulation |
Classification criteria for CAPS as modified from Asheron et al.42
For histopathologic confirmation, significant evidence of thrombosis must be present, although vasculitis may coexist occasionally.