Table 2.
Diagnostic steps in the assessment of aPL-positive patients
| Step 1. Assessment of aPL tests individually (2 positive tests at least 12 wk apart are important to rule out transient positivity during infections) | |
| LA test | The LA test is associated with highest risk for clinical events (compared with aCL and aβ2GPI) |
| The LA test should be interpreted with caution in anticoagulated patients because of false positive results | |
| aCL and aβ2GPI antibodies | Moderate-to-high titers* of aCL or aβ2GPI IgG or IgM have higher association with clinical events (compared with lower titers) |
| IgG positivity has a stronger association with clinical events (compared with IgM) | |
| Isolated moderate- to high-titer aCL or aβ2GPI IgA is rare with unknown clinical significance | |
| Step 2. Assessment of aPL profile (clinical judgement is needed if the LA test is performed during anticoagulation, the aPL profile is low risk, the aPL is tested only once, and the only positive aPL is aCL and/or aβ2GPI IgA) | |
| High-risk aPL profile | Positive LA and/or moderate- to high-titer* aCL or aβ2GPI IgG or IgM |
| Moderate-risk aPL profile | Negative LA and moderate- to high-titer* aCL or aβ2GPI IgG or IgM |
| Low-risk aPL profile | Negative LA and low titer* of aCL or aβ2GPI IgG or IgM |
Adapted from Garcia D, Erkan D. Diagnosis and management of the antiphospholipid syndrome. N Engl J Med. 378, 2010-2021, Copyright © 2018 Massachusetts Medical Society.
*
Our definition of moderate-to-high titer is ≥40 GPL/MPL units, and our definition for low titer is 20-39 GPL/MPL units. GPL, IgG phospholipid units; MPL, IgM phospholipid units.