Lupus Anticoagulant: Performance of a New, Fully Automated Commercial Screening and Confirmation Assay

摘要

Lupus anticoagulants (LAs) are acquired circulating anticoagulants that interfere with phospholipid (PL)-dependent coagulation tests and are frequently associated with thromboembolic disorders and obstetric complications. Detection of LAs is of major importance in patients with these conditions (1)(2). LAs are diagnosed according to the criteria proposed by the Scientific and Standardization Committee on LAS of the International Society of Thrombosis and Hemostasis (3). According to these criteria, a diagnosis of LA should follow a 4-step procedure respecting the following principles: (a) prolongation of 1 (or more) PL-dependent clotting test (screening test); (b) evidence of inhibition demonstrated after mixing equal amounts of patient and normal plasma (mixing test); (c) evidence that the inhibitor is PL dependent, as demonstrated by correction of the clotting defect in the presence of excessively high PL concentrations (confirmatory test); and (d) lack of specific inhibition of any coagulation factor (distinction from other coagulopathies by specific factor assays).Despite these criteria, diagnosis of LA remains a problem for the clinical laboratory. Contributing to these problems are the marked differences in sensitivity and specificity for the various LA screening assays that have been proposed, the lack of a universally accepted definition of a positive mixing test, technical variables affecting the various assays for LA, the difficulty with result interpretation, and the heterogeneous nature of LA itself (4)(5). At present, the most used screening tests for detecting LA are a dilute activated partial thromboplastin …