The anticardiolipin assay is required for sensitive screening for antiphospholipid antibodies

The importance of testing for anticardiolipin antibodies (aCL) in the diagnosis of antiphospholipid syndrome (APS) in patients with thrombosis has recently been challenged (ISTH SSC meeting, Boston 2002). We have analyzed the antiphospholipid serology of 123 patients with persistent antiphospholipid antibodies (aPL) attending our hematology department. The cohort was tested for anti‐β2‐glycoprotein I (β2‐GPI) antibodies and aCL of IgG and IgM class and for lupus anticoagulant (LA). Ninety‐six of these patients fulfilled Sapporo clinical criteria for APS and 70 of these patients had venous and/or arterial thrombosis. Patients with LA plus anti‐β2‐GPI antibodies had significantly higher levels of IgG aCL and anti‐β2‐GPI antibodies than those exhibiting positivity for only LA or anti‐β2‐GPI antibodies (P