Wednesday, October 03, 2007

Controversies in antiphospholipid syndrome

Terminology can be confusing. Diagnostic and treatment strategies are evolving. This update in Current Opinion in Hematology is timely.

Noteworthy points:

Among antiphospholipid antibodies, those which prolong the aPTT (so called Lupus anticoagulants) may carry a higher risk of thrombosis than anticardiolipin antibodies (OR 11.0 and 1.6 respectively). This marked difference may be biased by inclusion in the meta-analyses on which these data are based of patients with low titer anticardiolipin antibodies which are of doubtful clinical significance and do not meet current diagnostic criteria for antiphospholipid syndrome.

A common scenario is the need to evaluate a patient for thrombophilia after anticoagulants have been started. Lupus anticoagulant assays can be done on such patients but require special handling and advance notification to the laboratory.

Patients with antiphospholipid antibodies and venous thrombosis, following acute treatment with some form of heparin overlapped with warfarin, should be treated with warfarin adjusted to an INR of 2.0-3.0 long term for a duration of one year to indefinitely.

Data are less clear for patients with stroke and antiphospholipid antibodies. Absent another indication for anticoagulation warfarin adjusted to an INR of 1.4-2.8 or aspirin is suggested. For non-cerebral arterial thrombosis warfarin adjusted to an INR of 2.0-3.0 is recommended.

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