An evaluation of two commercial test procedures for the detection of lupus anticoagulant.

The authors have evaluated two commercial assays for lupus anticoagulants (LA), the DVVtest+DVV confirm (American Diagnostica, Greenwich, CT) and the PTT-LA+Staclot LA (Diagnostica Stago, Asnieres-Sur-Seine, France). The assays were compared with a previously described quantitative, semi-automated, and computer-assisted test, which is based on two assays, using the activated partial thromboplastin time (APTT) and the Russell's viper venom time (RVVT), respectively. Thirty well-characterized LA-positive and 30 LA-negative plasma samples were used to test the commercial assays. In some samples, both commercial tests failed to detect weak or moderately strong LAs. The sensitivity was 80% for the DVVtest+DVV confirm and 67% for the PTT-LA+Staclot LA. However, by applying both the two commercial tests to all plasma samples, 29 of 30 LA-positive plasma samples were diagnosed (sensitivity 97%). No false positive test results were found (specificity 100%).