Current clinical and laboratory practice for the investigation of the antiphospholipid syndrome: findings from the 2008 Australasian antiphospholipid antibody survey.

BACKGROUND

The antiphospholipid syndrome (APS) is an autoimmune condition characterised by vascular thromboses and/or pregnancy morbidity, and its diagnosis currently requires laboratory evidence for the presence of antiphospholipid antibodies (aPL). aPL are identified using a large number of laboratory procedures based on one of two distinct test processes, namely 'solid' or 'liquid' phase assays. The former include anticardiolipin antibodies (aCL) and anti-beta-2-glycoprotein-I antibodies (aB2GPI), while the latter are centred on clot-based tests used to identify the lupus anticoagulant (LA). Depending on their clinical presentation, affected individuals might be seen by a variety of clinical specialties including general physicians and general practionners, with a potentially wide variation in the aPL assays requested.

METHODS

The current report summarises findings from the '2008 Australasian antiphospholipid antibody survey', a simple 5-step survey that assessed current clinical and laboratory practice in the investigation of APS. The survey was despatched via various clinical and scientific professional bodies.

RESULTS

Responses were received from 130 scientific and clinical personnel, primarily haematology based (94/130; 72%) or immunology based (34/130; 26%). Most respondents (97/130; 75%) ordered or recommended tests for solid phase aPL testing, and most also attempted to grade these tests and their isotypes. Most were familiar with aCL and aB2GPI testing, and tended to request primarily IgG and IgM isotypes of these antibodies. Only a small number of respondents requested/recommended IgA isotype testing of these antibodies or the other solid phase aPL assays (e.g., anti-prothrombin). A similar number of respondents (104/130; 80%) also ordered or recommended tests for LA, and most also attempted to grade these tests and their isotypes. Some discipline-related biases were also evident, in that 32/34 (94%) of immunology-based respondents identified that they ordered or recommended specific solid phase tests for aPL, whereas only 62/94 (66%) of haematology-based respondents did so. In contrast, 83/94 (88%) of haematology-based respondents identified that they ordered or recommended specific LA test procedures, whereas only 18/34 (53%) of immunology-based respondents did so.

CONCLUSION

To our knowledge, this report represents the first ever attempt to survey a wide range of clinical and scientific personnel regarding ordering and recommending practices for aPL testing, and provides a snapshot of current clinical and laboratory practice for the investigation of APS in Australia and New Zealand. Most respondents to our survey still consider the immunoglobulin G (IgG) aCL test to be a useful first-line solid phase aPL test, and the dilute Russell's viper venom time (dRVVT) assay to be the most useful LA test.