Secondary prevention in thrombotic antiphospholipid syndrome

Secondary prevention of venous thromboembolism in antiphospholipid syndrome (APS) is usually made using vitamin K antagonists (VKAs) to maintain an international normalized ratio (INR) between 2.0 and 3.0. The optimal intensity of anticoagulation was determined in two prospective randomized controlled trials, both excluding the benefit of more intense anticoagulation. The same regimen is also recommended in patients with APS and arterial thromboembolism as aspirin does not appear to protect against recurrences. The duration of treatment is usually indefinite because of a substantial risk of recurrence.

Influence of different IgG anticardiolipin antibody cut-off values on antiphospholipid syndrome classification

BACKGROUND

While medium to high titers of anticardiolipin (aCL) antibodies, defined as >40 GPL units or >99th percentile, is a laboratory criteria for the 'definite' diagnosis of antiphospholipid syndrome (APS), agreement between the two cut-offs has not been validated.

OBJECTIVE

To validate the current aCL laboratory criterion by verifying the effect of the two cut-offs on APS classification.

PATIENTS/METHODS

Ninety aCL positive APS patients were selected on the basis of their GPL values above the 99th percentile (17.4 GPL), which was calculated by testing 100 age- and sex-matched healthy subjects.

RESULTS

A significant difference in the IgG positivity (P < 0.0001) was found between the APS laboratory profiles as 20 out of the 24 (83.3%) patients with single positivity (aCL alone), six out of the 23 (26.1%) with double positivity (aCL plus lupus anticoagulant or anti-beta(2)glycoprotein I), and none out of the 43 with triple positivity (aCL plus lupus anticoagulant and anti-beta(2)glycoprotein I) had titers between the 99th percentile and 40 GPL units. Moreover, the rate of aCL values between the 99th percentile and 40 GPL units was significantly higher (P < 0.0001) in patients with pregnancy morbidity (73.7%) as compared to those with vascular thrombosis (16.9%) and those with both conditions (16.7%).

CONCLUSION

The 99th percentile cut-off level seems more sensitive than the >40 GPL value for APS classification, as it includes subjects with aCL positivity alone as well as patients with pregnancy morbidity.