High frequency of inadequate test requests for antiphospholipid antibodies in daily clinical practice.

Background: We have empirically noted that many physicians routinely request anti-phospholipid antibodies (aPL) without a correct clinical indication. The aim of this study was to evaluate retrospectively whether aPL testing at our Thrombosis Centre was justified.

Methods: Medical records from 520 subjects for aPL screening tests for various clinical conditions were reviewed. The aPL screening tests were: lupus anticoagulant (LA), anti-cardiolipin antibodies (aCL) and anti-β(2) glycoptotein I (aβ(2) GPI). Requests for aPL screening were divided into justified, potentially justified or not adequately justified.

Results: aPL testing requests were considered justified in 358 (69%) patients, potentially justified in 66 (12.6%) and not adequately justified in 96 (18.4%). LA was positive in 65 (18%) of justified requests and in only one (1%) of the 96 potentially justified requests. None of the 66 not adequately justified for aPL testing was positive for LA. aβ(2) GPI was positive in 63 (17.6%) of the 358 justified, in four (6%) of the 66 potentially justified and in five (5.2%) of the 96 not adequately justified requests; aCL IgG were positive in 59 (16.4%) of the 358 justified and in five (7.5%) and six (6.2%) of the potentially justified and not adequately justified requests, respectively. The presence of the triple aPL positivity was found exclusively in the justified requests.

Conclusions: This study suggests that requests for aPL tests should be addressed more adequately. This work could be an example of how to focus attention on requests for laboratory tests especially on the basis of valid clinical criteria before the analyte is measured.