From the Research
The British Society of Haematology guidelines for antiphospholipid antibody (aPL) testing recommend a stepwise approach to diagnosis of antiphospholipid syndrome (APS), with initial screening including lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and anti-β2 glycoprotein I antibodies (aβ2GPI), as supported by the most recent study 1.
Key Recommendations
- Initial screening should include LA, aCL, and aβ2GPI, with IgG and IgM isotypes for both aCL and aβ2GPI.
- Testing should be performed when patients present with unprovoked venous thromboembolism, arterial thrombosis, pregnancy morbidity, or unexplained prolonged activated partial thromboplastin time (APTT).
- For diagnosis of APS, persistent positivity is required, with testing repeated after 12 weeks, as stated in 2.
- Medium to high titer antibodies (>40 GPL/MPL units for aCL or >99th percentile for aβ2GPI) carry greater clinical significance, as noted in 3.
- LA testing requires specialized coagulation assays including screening, mixing, and confirmatory tests, performed when the patient is not on anticoagulation or at least 12 hours after last dose of direct oral anticoagulants.
- Triple positivity (positive for LA, aCL, and aβ2GPI) indicates highest thrombotic risk, as highlighted in 4.
Clinical Considerations
- Clinicians should correlate laboratory findings with clinical presentation, as transient aPL positivity can occur during infections or with certain medications without clinical significance, as mentioned in 1.
- The guidelines emphasize standardized laboratory techniques, proper sample handling, and interpretation by experienced personnel to minimize false results, as emphasized in 3.
- Aspirin may be beneficial in preventing APS manifestations in aPL-positive patients, particularly those with systemic lupus erythematosus (SLE) or autoimmune thrombocytopenia (AIT), as suggested by 5.