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Refinement of the cutoff values of the Hemos IL AcuStar assay for the detection of anticardiolipin and anti–beta 2 glycoprotein‐1 antibodies
Author(s) -
Fontana P.,
Poncet A.,
LindhoffLast E.,
Moerloose P.,
Devreese K. M.
Publication year - 2014
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.12732
Subject(s) - anticardiolipin antibodies , antibody , glycoprotein , cutoff , medicine , microbiology and biotechnology , immunology , biology , physics , quantum mechanics
Summary Background The Hemos IL AcuStar antiphospholipid assay (Instrumentation Laboratory, Bedford, MA, USA ) is a fully automated assay using chemiluminescent technology for the detection of anticardiolipin and anti–beta 2 glycoprotein‐1 antibodies. This assay showed excellent agreement between results of different laboratories. The cutoff values to define positivity were calculated in 250 healthy blood bank donors but were associated with large confidence intervals ( CIs ). Objective The objective of this study was to more precisely determine the cutoff values of the Hemos IL AcuStar antiphospholipid assay by increasing the number of healthy blood bank donors through a multicenter study and by applying a normalization procedure of the distribution of each antibody. Methods Five laboratories participated to this study, allowing the inclusion of 626 samples. We used a Box–Cox power transformation method to normalize the distribution and calculate the 99th percentile and the corresponding 95% CI for each antibody. Results The revised cutoff values were overall lower than those initially calculated with more stringent CIs and yielded a 4.2% increase in sensitivity with a 2.7% decrease in specificity regarding thrombotic events or obstetric complications. Conclusions We provide refined cutoff values for the detection of anticardiolipin and anti–beta 2 glycoprotein‐1 antibodies with the Hemos IL AcuStar Antiphospholipid assay that should be preferred for routine use.