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A multicenter study to assess the reproducibility of antiphospholipid antibody results produced by an automated system
Author(s) -
Devreese K. M.,
Poncet A.,
LindhoffLast E.,
Musial J.,
Moerloose P.,
Fontana P.
Publication year - 2017
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.13560
Subject(s) - repeatability , reproducibility , antiphospholipid syndrome , coefficient of variation , medicine , blinded study , lupus anticoagulant , antibody , immunology , chemistry , chromatography
Essentials Inter‐lab variation studies for antiphospholipid antibodies (aPL) with the same assay are lacking. We carried out an assessment of repeatability and reproducibility of an automated aPL assay. High intra‐center repeatability for anticardiolipin and aβ 2 GPI makes duplicate testing unnecessary. Inter‐lab reproducibility was high except for aβ2GPI IgG.Summary Background Inter‐assay variability is a well‐known problem in antiphospholipid antibody testing, because of the lack of standardization. Inter‐laboratory reproducibility for the same assay is similarly important. Objectives Testing repeatability and reproducibility of Hemos IL ® AcuStar for anticardiolipin ( aCL ) and antiβ2‐glycoprotein I antibodies (aβ2 GPI ) IgG and IgM. Patients/Methods In this observational study, out of 420 samples from the thrombophilia centers of Ghent and Geneva, 100 samples were randomly selected and successively analyzed in three centers: Ghent (C1, in duplicate for repeatability evaluation), Geneva (C2) and Frankfurt (C3). Results Results from 99 samples were available, including 25 from patients with antiphospholipid syndrome ( APS ) and 74 from non‐ APS patients. The intra‐center repeatability expressed as intra‐class correlation coefficient ( ICC ) was higher than 0.99 for each parameter. Differences between two measurements rarely exceeded 1 U mL −1 for values below 100 U mL −1 , except for aβ2GPI IgG, where differences varied from −4 to 4 U mL −1 . The inter‐center ICC s were higher than 0.99, except for aCL IgM ( ICC = 0.961). These ICCs remained high even when considering values below 100 U mL −1 (0.943, 0.964 and 0.977 for aCL IgG, aCL gM and aβ2 GPI IgM, respectively), except for aβ2 GPI IgG ( ICC = 0.652). Qualitative comparison showed less than 5% discordant classification between centers, with somewhat more discordant results for aβ2GPI IgG. Conclusions In terms of discriminating properties, the Hemos IL ® AcuStar has excellent intra‐center repeatability and a good inter‐center reproducibility for aCL IgG, aCL IgM and aβ2 GPI IgM. Some concern may arise for aβ2 GPI IgG.