Evaluation of three commercial ELISA kits for anticardiolipin and anti-beta2-glycoprotein I antibodies in the laboratory diagnosis of the antiphospholipid syndrome.
BACKGROUND
The laboratory criteria of the antiphospholipid syndrome (APS) include lupus anticoagulant (LAC), anticardiolipin antibodies (aCL) and anti-β2glycoprotein I antibodies (aβ2GPI) IgG or IgM.


METHODS
We evaluated three commercial ELISAs for aCL and aβ2GPI IgG and IgM: Asserachrom® ('Stago'), Bio-Rad ('BR') and the Bindazyme™ (the Binding Site, 'BS').


RESULTS
Results of all assays and of LAC were correlated with the clinical background (n=228). Sensitivity for Stago/BS/BR aCL IgG was 14%/15%/18%, for aCL IgM 1%/5%/4%, for aβ2GPI IgG 9%/10%/17% and for aβ2GPI IgM 4%/4%/3%. The specificity for Stago/BS/BR for all assays ranged from 86% to 98%. The positive predictive value (PPV) for Stago/BS/BR aCL IgG was 46%/52%/40%, for aCL IgM 8%/36%/19%, for aβ2GPI IgG 70%/67%/45% and for aβ2GPI IgM 23%/23%/20%. Combining LAC with aCL and aβ2GPI antibodies increased the sensitivity (Stago/BS/BR IgG: 26%/27%/31%, IgM: 22%/21%/26%) and PPV (Stago/BS/BR IgG: 41%/46%/36%, IgM: 34%/40%/36%). Comparing the diagnostic power of the tests, only Stago/BS aβ2GPI IgG had a Chi-square P-value lower than 0.05. The combination of LAC and IgG ELISAs of BS resulted in the lowest P-value (0.098) compared to the other combinations.


CONCLUSIONS
All evaluated ELISAs are a practical tool in the laboratory diagnosis of APS. The diagnostic performance shows slight differences between the ELISAs from the different manufacturers.
Decavele
A S
AS
Coagulation Laboratory, Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, De Pintelaan 185, Ghent, Belgium.
Schouwers
S
S
Devreese
K M J
KM
D017153:Antibodies, Anticardiolipin / Q000097:blood*; D016736:Antiphospholipid Syndrome / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic / Q000592:standards*; D012680:Sensitivity and Specificity; D053482:beta 2-Glycoprotein I / Q000276:immunology*
D017153:Antibodies, Anticardiolipin; D011933:Reagent Kits, Diagnostic; D053482:beta 2-Glycoprotein I