DIAGNOSTIC SIGNIFICANCE OF TESTING ANTI-BETA2-GLYCOPROTEIN I ANTIBODIES FOR THE ANTIPHOSPHOLIPID SYNDROME
Abstract number: P-S-528
Kato1 M., Atsumi1 T., Sakai1 Y., Amengual1 O., Bohgaki1 T., Kataoka1 H., Horita1 T., Yasuda1 S., Koike1 T.
1Medicine II, Hokkaido University Graduate School of Medicine, Sapporo, Japan
How-to-cite Kato M, Atsumi T, Sakai Y, Amengual O, Bohgaki T, Kataoka H, Horita T, Yasuda S, Koike T. DIAGNOSTIC SIGNIFICANCE OF TESTING ANTI-BETA2-GLYCOPROTEIN I ANTIBODIES FOR THE ANTIPHOSPHOLIPID SYNDROME. J Thromb Haemost 2007; 5 Supplement 2: P-S-528
Introduction: A preconference workshop in 11th International Congress on antiphospholipid antibodies, held in Sydney, proposed a revision of the Sapporo Criteria for antiphospholipid syndrome (APS). In this proposed criteria (Sydney revision), IgG/M anti-beta2-glycoprotein I antibodies (anti-b2GPI) were included as part of the laboratory criteria. Although methodology and standardization limitations have been pointed out, one of the advantages of this criterion is that the committee defines a cut-off value for positive anti-b2GPI as >99th percentile of controls. In this study, we set-up the anti-b2GPI assay according to the criterion, and investigated its value for the diagnosis of APS.
Methods: This study comprised 2 parts. In the first part, IgG/M anti-b2GPI were measured in 102 patients with APS, defined by Sapporo Criteria, and prevalence of anti-b2GPI was investigated. In the second part of the study, IgG/M anti-b2GPI were determined in 243 consecutive patients who visited our autoimmune disease clinic. Anti-b2GPI ELISA was performed using irradiated ELISA plates (Maxisorp), and the cut-off values were defined as above. The relative risk (RR) for having thrombosis was approximated by Odd's ratio.
Results: In 102 APS patients, prevalences of only IgG, only IgM, both IgG and IgM anti-b2GPI were 30, 10, 13%, repectively, thus total 53% of APS patients had IgG/M anti-b2GPI. In the second part, 61 patients had a history of thrombosis. IgG/M anticardiolipin antibodies (aCL) and anti-b2GPI were concordantly prevalent in 87%. The RR [95%CI] of IgG/M anti-b2GPI for thrombosis was 6.28 [3.03-13.02], being higher compared with that of IgG/M aCL (5.43 [2.52-12.71]). Three patients with thrombosis (5%) had anti-b2GPI in the absence of aCL or lupus anticoagulant.
Conclusions: Additional anti-b2GPI testing may improve the diagnostic yield of APS.
References: Miyakis S, Lockshin MD, Atsumi T,et al. J Thromb Haemost 4; 295-306, 2006