ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 164

Reliability of Lupus Anticoagulant and Anti-Phosphatidylserine/Prothrombin Autoantibodies in Antiphosphospholipid Syndrome: A Multicenter Study

Massimo Radin1, Irene Cecchi2, Elena Rubini3, Anna Scotta4, Roberta Rolla5, Barbara Montaruli6, Patrizia Pergolini5, Giulio Mengozzi4, Elena Muccini4, Antonella Vaccarino7, Dario Roccatello8 and Savino Sciascia9, 1Department of Clinical and Biological Sciences, Center of Research of Immunopathology and Rare Diseases- Coordinating Center of Piemonte and Valle d’Aosta Network for Rare Diseases, Department of Clinical and Biological Sciences, University of Turin, Italy, Turin, Italy, 2Center of Research of Immunopathology and Rare Diseases- Coordinating Center of Piemonte and Valle d’Aosta Network for Rare Diseases, Department of Clinical and Biological Sciences, University of Turin, Italy, Turin, Italy, 3Center of Research of Immunopathology and Rare Diseases- Coordinating Center of Piemonte and Valle d’Aosta Network for Rare Diseases, Department of Clinical and Biological Sciences, University of Turin and S. Giovanni Bosco Hospital, Turin, Italy., Turin, Italy, 4University of Turin, Turin, Italy, 5University of Turin, Novara, Italy, 6Ospedale Mauriziano, Turin, Italy, 7Ospedale S. Giovanni Bosco, Turin, Italy, 8Center of Research of Immunopathology and Rare Diseases- Coordinating Center of Piemonte and Valle d’Aosta Network for Rare Diseases, Department of Clinical and Biological Sciences, University of Turin and S. Giovanni Bo, Turin, Italy, 9Center of Research of Immunopathology and Rare Diseases- Coordinating Center of Piemonte and Valle d’Aosta Network for Rare Diseases, Department of Clinical and Biological Sciences, University of Turin, Italy, Center of Research of Immunopathology and Rare Diseases- Coordinating Center of Piemonte and Valle d’Aosta Network for Rare Diseases, Department of Clinical and Biological Sciences, University of Turin, Italy, Torino, Italy

Meeting: 2018 ACR/ARHP Annual Meeting

Keywords: , , ,

Session Information

Date: Sunday, October 21, 2018

Title: Antiphospholipid Syndrome Poster

Session Type: ACR Poster Session A

Session Time: 9:00AM-11:00AM

Background/Purpose:

Correct interpretation of lupus anticoagulant (LA) tests is crucial for diagnosis of antiphospholipid syndrome (APS). However, testing patients during vitamin K antagonist (VKA) or other anticoagulant treatment remains a contentious issue and has been discouraged by official guidelines because of interpretational problems affecting the mixing test.

Methods:

We enrolled 60 patients who met one of the following inclusion criteria: 1) Fulfilled the diagnosis of thrombotic APS defined as per Sidney criteria; 2) Patients with thrombosis and suspected APS not completely fulfilling the laboratory criteria, as follows: a) and inconstant previous LA positivity; and/or b) low-medium titers aPL (defined as levels of aCL IgG/IgM or anti-β2GPI IgG/IgM 10-30 GPL/MPL aPL) with no LA positivity. aPL testing was performed in a blind fashion in 4 centers undergoing periodic external quality assessment.

Results:

 The mean age at was 50 years old (SD ±11) (F:M 71,7% : 28,3%). Forty-three patients (72%) had a confirmed diagnosis of thrombotic APS (arterial 58%; venous 56%), and 17 patients presented with thrombosis and inconstant LA positivity (N. 7; 41%) and/or with low-medium titers  (N. 10;59%). Categorical agreement for LA among the centers, as expressed by Cohen’s kappa coefficients, ranged between 0.41 and 0.60 (corresponding to moderate agreement). The correlation among quantitative results at the 4 sites for aPS/PT IgG was strong (Cohen’s kappa coefficients=0.81–1. Spearman rho 0.84). We observed 27 (45 % of the total) cases (15/20, 75% patients on VKA) in which LA results were discordant (as defined by lack of agreement in ≥3 laboratories) or inconclusive. Conversely, in those cases, we observed a good correlation for aPS/PT IgG testing (Cohen’s kappa coefficients=0.81–1, Spearman rho 0.86). aPS/PT testing showed an overall agreement of 83% (up to 90% in patients receiving VKA), providing an overall increase in test reproducibility of + 28% when compared to LA, becoming even more evident (+65%) when analyzing patients on VKA.  

Conclusion:

Despite the progress in the standardization of aPL testing, we observed up to 45% of discrepant results for LA, even higher in patients on VKA. Our findings highlight that some discordances in the reliability of LA testing still exist. The introduction of aPS/PT antibody testing into the diagnostic process of APS might represent a further diagnostic tool, especially when LA is not available or the results are uncertain.

Disclosure: M. Radin, None; I. Cecchi, None; E. Rubini, None; A. Scotta, None; R. Rolla, None; B. Montaruli, None; P. Pergolini, None; G. Mengozzi, None; E. Muccini, None; A. Vaccarino, None; D. Roccatello, None; S. Sciascia, None.

To cite this abstract in AMA style:

Radin M, Cecchi I, Rubini E, Scotta A, Rolla R, Montaruli B, Pergolini P, Mengozzi G, Muccini E, Vaccarino A, Roccatello D, Sciascia S. Reliability of Lupus Anticoagulant and Anti-Phosphatidylserine/Prothrombin Autoantibodies in Antiphosphospholipid Syndrome: A Multicenter Study [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 9). https://acrabstracts.org/abstract/reliability-of-lupus-anticoagulant-and-anti-phosphatidylserine-prothrombin-autoantibodies-in-antiphosphospholipid-syndrome-a-multicenter-study/. Accessed .

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