Assessing the usefulness of anticardiolipin antibody assays: a cautious approach is suggested by high variation and limited consensus in multilaboratory testing.
An anticardiolipin antibody (ACA) assay has become a laboratory standard for the detection of antiphospholipid antibodies. We evaluated data from a quality assurance program to assess ACA assay usefulness. Cross-laboratory (n = 56) testing of 12 serum samples yielded interlaboratory coefficients of variation (CVs) for lgG ACA and IgM ACA that were higher than 50% in 17 (71%) of 24 cases. The situation for testing consensus was of equal concern. Total consensus occurred in 6 (25%) of 24 cases. General consensus (interlaboratory agreement, 90% or more) was obtained in 10 (42%) of 24 cases. In the majority of test cases, laboratories could not agree on whether a serum sample tested was ACA-positive or ACA-negative. Differing method-related issues also were evident; some methods tended toward higher or lower ACA values. Method-based majority consensus differed from participant majority consensus on many test occasions. Exceedingly high interlaboratory result variation, combined with a general lack of test result grading consensus and method-based variation, indicate that a cautious clinical approach toward laboratory findings is prudent. Laboratory tests should be repeated at least once before making a clinical diagnosis of any anti-phospholipid syndrome-like disorder.
Favaloro
Emmanuel J
EJ
Department of Haematology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Western Sydney Area Health Service, New South Wales, Australia.
Silvestrini
Roger
R
D017153:Antibodies, Anticardiolipin / Q000097:blood*; D003955:Diagnostic Tests, Routine / Q000592:standards*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015588:Observer Variation; D011785:Quality Assurance, Health Care; D012016:Reference Values; D015203:Reproducibility of Results
D017153:Antibodies, Anticardiolipin