Session Information
Title: Antiphospholipid Syndrome: Clinical Manifestations and New Biomarkers in Antiphospholipid Syndrome
Session Type: Abstract Submissions (ACR)
Background/Purpose:
Anticardiolipin (aCL) antibody assays are sensitive for the detection of antiphospholipid antibodies (aPL) in patients with the Antiphospholipid syndrome (APS) but are known to have suboptimal clinical specificity due to cross-reaction with infectious diseases and other non-APS sera. The APhL ELISA® is an immunoassay that detects antibodies to negatively charged phospholipids in the presence of β2GPI and has been shown to be more specific than the aCL in the diagnosis of APS. The objective of this study was to evaluate and compare the clinical sensitivity and specificity of the APhL ELISA® with two aCL
Methods:
Serum samples from confirmed primary and secondary APS patients (n=54), syphilis (n=20), infectious diseases (n=30), hyperglobulinemias (n=15), paraproteinemias (n=15) and healthy controls (n=54) were evaluated for IgG and IgM aPL antibodies in the APhL ELISA® (Louisville APL Diagnostics) and in two aCL assays (Louisville APL Diagnostics, Inc; LAPL) and in a laboratory developed test (LDT). Samples were obtained from Prof Meroni’s laboratory and kits were provided at no cost by the manufacturer. Assays were considered positive when above the stated cut-off for each test. Clinical sensitivities, specificities, positive predictive (PPV) and negative predictive values (NPV) were calculated individually by isotype or combined (IgG and IgM) for each assay.
Results:
|
|
APhL ELISA® IgG |
APhL ELISA® IgM |
APhL ELISA® IgG and IgM |
aCL LAPL IgG |
aCL LAPL IgM |
aCL LAPL (IgG and IgM) |
aCL LDT IgG |
aCL LDT IgM |
aCL LDT IgG and IgM |
|
Clin Sens % |
83.0 |
92.5 |
94 |
83.3 |
90.7 |
96 |
73.5 |
39.6 |
81.0 |
|
Clin Spec% |
95.5 |
95.5 |
91 |
77.6 |
59.7 |
52.0 |
73.1 |
77.6 |
61.0 |
|
PPV% |
88.0 |
89.0 |
81.0 |
56.9 |
52.6 |
44.0 |
52.0 |
42.0 |
45.2 |
|
NPV% |
92.0 |
96.9 |
97.6 |
91.7 |
94.1 |
97.2 |
87.5 |
76.4 |
91.1 |
Conclusion:
The APhL ELISA® showed better PPV, NPV, combined sensitivities and specificities whether analyzed for IgG or IgM independently or combined, when compared to the two aCL assays. The APhL ELISA® may be used as a first line of testing and certainly could be recommended as a confirmatory assay for the diagnosis of APS.
Disclosure:
C. Grossi,
None;
M. Borghi,
None;
E. Papalardo,
Louisville APL Diagnostics ,
3;
S. S. Pierangeli,
Louisville APL Diagnostics, Inc,
4;
P. L. Meroni,
None.
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