Session Information
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: The APS ACTION International Clinical Database and Repository (“Registry”) was created to study the natural course of disease over 10 years in persistently aPL-positive patients with/without other systemic autoimmune diseases. The network consists of five international core laboratories created to confirm aPL-positivity and for mechanistic studies. In this study we aimed to assess the agreement between inclusion and core laboratory anticardiolipin (aCL) and anti-β2glycoprotein I antibodies (aβ2GPI) ELISA
Methods: A secure web-based data capture system is used to store patient information including demographics, aPL/APS history, and aPL data. The inclusion criteria are positive lupus anticoagulant (LA) test based on the ISTH recommendations and medium-to-high titer aCL and/or aβ2GPI tested at least twice within one year prior to enrollment. The baseline samples of registry patients were re-tested for aCL and aβ2GPI (IgG, IgM and IgA with the QUANTA Lite® ELISA kits, Inova Diagnostics) at five different core laboratories. As part of this validation exercise, two different cut off values assays for aPL ELISA were arbitrarily used (20 and 40 GPL/MPL/APL for IgG, IgM and IgA, respectively). Data was analysed using SPSS (IBM Software, NY).
Results: Four hundred and ninety-seven patients were included. Categorical agreement between the baseline values at inclusion vs. core laboratory results is summarized in Table 1. Cohen’s kappa coefficients ranged between 0.61 and 0.80 (as substantial agreement). Overall, the correlation between quantitative results in the aCL and aβ2GPI was better for IgM and IgA compared to IgG (Spearman rho 0.789 and 0.666 vs. 0.600 for aCL and rho 0.892 and 0.744 vs. 0.432 for aβ2GPI).
Conclusion: aCL and aβ2GPI results showed very good categorical agreement between aPL testing at inclusion and core laboratories results. This agreement increases when considering high titer samples (>40 units). Based on the evaluations performed by the APS ACTION core laboratories, different ELISA tests used for inclusion displayed substantially equivalent performance for the detection of aCL and aβ2GPI. However, some non-substantial misclassification in terms of titers can be observed, especially for IgG isotype. Table 1: Categorical agreement between the baseline values (BV) at inclusion vs. core laboratory (CR) results
|
|
|
cut off 40 %(BV/CR) |
cut off 20 %(BV/CR) |
| aCL | IgG |
81.7% (368/450) |
81.6% (367/450) |
| IgM |
85.2% (381/447) |
79.2% (354/447) |
|
| IgA |
90.8% (99/109) |
83.5% (91/109) |
|
| aβ2GPI | IgG |
82.2% (287/349) |
79.7% (278/349) |
| IgM |
88.9% (346/389) |
86.1% (335/389) |
|
| IgA |
88.5% (108/122) |
82.2% (100/122) |
To cite this abstract in AMA style:
Sciascia S, Willis R, Pengo V, Krilis S, Andrade D, Erkan D, Bertolaccini ML, . OBOAA. Antiphospholipid Syndrome Alliance for Clinical Trials & International Networking (APS ACTION) Clinical Database and Repository Analysis: The Comparison of Real World and Core Laboratory Antiphospholipid Antibody ELISA Results [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/antiphospholipid-syndrome-alliance-for-clinical-trials-international-networking-aps-action-clinical-database-and-repository-analysis-the-comparison-of-real-world-and-core-laboratory-antiphospholi/. Accessed .« Back to 2016 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/antiphospholipid-syndrome-alliance-for-clinical-trials-international-networking-aps-action-clinical-database-and-repository-analysis-the-comparison-of-real-world-and-core-laboratory-antiphospholi/