Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Comparative Evaluation of Different Immunoassays for the Detection of Antiphospholipid Antibodies: Report of a Wet Workshop during the 13th International Congress on Antiphospholipid Antibodies.

Forastiero9,  Ricardo, Papalardo8,  Elizabeth, Morin4,  Kerrie, Quirbach4,  Catherine, Lakos6,  Gabriella, Mattias5,  Karl, Albesa3,  Roger

Bio-Rad Laboratories, Hercules, CA
Bio-Rad Laboratories, Her
INOVA Diagnostics, San Diego, CA
Instrumentation Laboratories, Bedford, MA
Phadia GMBH, Freiburg, Germany
TheraTest Laboratories, Lombard, IL
Univ of TX Med Branch, Galveston, Galveston, TX
Univ of TX Med Branch, Galveston, TX
Universidad Favaloro, Buenos Aires Argentina

Background:

The performance and standardization of antiphospholipid (aPL) laboratory tests used in the confirmation of diagnosis of Antiphospholipid Syndrome (APS) is still a matter of debate and concern. In addition, recently novel methodologies and platforms for the detection of aPL antibodies have become available, but proper inter-assay simultaneous comparisons have not been carried out. Objective: to evaluate the performance of different ELISAs and other new immunoassays for the detection of aCL and ab2GPI antibodies (IgG, IgM) in a wet workshop at the 13th International Congress on Antiphospholipid Antibodies.

Methods:

Aliquots of 26 un-identified APS serum samples (diagnosis according to Sapporo modified criteria) and 21 controls (14 from healthy individuals and 7 from patients with infectious diseases) were distributed to all participants/groups. All serum samples were evaluated in various aCL and ab2GPI ELISAs, in the APhL ELISA® (an assay that utilizes a mixture of negatively charged phospholipids instead of cardiolipin, Louisville APL Diagnostics (LAPL)] and in in three fully automated methodologies: HemosIL® AcuStar Antiphospholipid assay panel, a chemiluminescent immunoassay panel on the ACL AcuStar™[Instrumentation Laboratory (IL)] a fluoro-enzyme immunoassay (Phadia) and in the BioPlex 2200, random access, multiplex testing immunoassay system (Bio-Rad), using either an automated or "manual" platforms (see table). All kits were evaluated as per the manufacturers' instructions and results were expressed in their respective units of measurement. The workshop was open to congress participants who registered for the event. Samples were evaluated in the different assays at least on two separate occasions.

Results:

Clinical sensitivities and specificities and positive predictive values were calculated.

ManufacturerAssayMethod/InstrumentationClinical sensitivity (%)Clinical Specificity (%)PPV
Bio-RadaCLGMMultiplex/BioPlex2200100950.95
Bio-Radab2GPIGMMultiplex/BioPlex2200100950.95
Bio-RadaCL GMELISA/PhD100950.95
Bio-Radab2GPIGMELISA/PhD100910.92
ILHemoSIL aCL GMChemiluminescent/Acustar100950.95
ILHemoSIL ab2GPIGMChemiluminescent/Acustar1001001.0
INOVAQUANTA LITE™aCL GMELISA/manual96910.92
INOVAQUANTA LITE™ ab2GPIGMELISA/manual881001.0
LAPLAPhL GMELISA/manual1001001.0
Phadia EliAaCL GMELISA/Phadia 2501001001.0
Phadia EliAab2GPIGMELISA/Phadia 250100950.95
TheratestaCL GMELISA/DSX21001001.0
Theratestab2GPIGMELISA/DSX2100950.9

Although not all the assays reported the titers of aCL and ab2GPI antibodies in the same units, the correlation of positive titers among the assays was excellent. All the healthy control samples were correctly identified by all groups as negative. Some of the ab2GPI tests reported positive one of the infectious disease sample. All the assays, but in particular the AcuStar chemiluminescent immunoassay panel and the BioPlex2200 assays showed excellent intra-assay variation (<10 % CV).

Conclusions:

All aCL and b2GPI tests showed excellent clinical sensitivities, specificities and positive predictive values and good agreement with respect to the levels of the IgG and IgM antibodies, regardless of assay type, or whether tests were done using automated or "manual" systems. New methodologies for the detection of aPL antibodies look promising and comparable to currently approved ELISA tests. This study validates current recommendations of the Sapporo revised criteria to use aCL and ab2GPI for proper confirmation of diagnosis of APS.

To cite this abstract, please use the following information:
Forastiero, Ricardo, Papalardo, Elizabeth, Morin, Kerrie, Quirbach, Catherine, Lakos, Gabriella, Mattias, Karl, et al; Comparative Evaluation of Different Immunoassays for the Detection of Antiphospholipid Antibodies: Report of a Wet Workshop during the 13th International Congress on Antiphospholipid Antibodies. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :2252
DOI: 10.1002/art.30015

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