Session Information
Title: Antiphospholipid Syndrome: Clinical Manifestations and New Biomarkers in Antiphospholipid Syndrome
Session Type: Abstract Submissions (ACR)
Background/Purpose:
Antiphospholipid Syndrome (APS) is characterized by the presence of antibodies to phospholipids (aPL) and to β2glycoprotein I (β2GPI) in patients with thrombosis or pregnancy morbidity. Several studies provided evidence that antibodies to domain 1 of β2GPI (β2GPI-D1) represent a promising biomarker for the diagnosis and risk assessment of APS. Several immunoassays have been described to detect those antibodies, but harmonization of those tests as well as correlation of those assays has not been properly addressed. Here we aimed to compare two assays for the detection of anti-β2GPI-D1 antibodies using clinically defined patients samples.
Methods:
A total of 72 APS patients and 45 controls (including healthy individuals, patients with infectious or autoimmune diseases) were tested for anti-β2-GPI antibodies by ELISA (in-house, London, UK and INOVA Diagnostics, San Diego, US) and for anti-β2GPI-D1 by QUANTA Flash CIA (INOVA) and by ELISA (in-house, London, UK). History of thrombosis was known for 94 patients (39 with and 55 without history of thrombosis).
Results:
Both anti-β2GPI-D1 assays showed good qualitative (79.5%, 95% CI 71.0-86.4; kappa=0.60, 95% CI 0.46-0.74) and quantitative agreements (spearman`s rho=0.76, 95% CI 0.67-0.83) as well as similar discrimination between APS patients and controls as shown by ROC analysis.
|
Comparison between assays |
|||
|
Qualitative (Total Agreement %/kappa) Quantitative (Spearman) |
B2 ELISA (INOVA) |
D1 ELISA (UK) |
D1 CIA |
|
B2 ELISA (UK ) |
88.9 (0.77) 0.82 (0.75-0.87) |
86.3 (0.73) 0.83 (0.76-0.88) |
89.7 (0.79) 0.84 (0.78-0.89) |
|
B2 ELISA (INOVA) |
/ |
82.1 (0.65) 0.68 (0.57-0.77) |
85.5 (0.71) 0.76 (0.67-0.83) |
|
D1 ELISA (UK) |
/ |
/ |
79.5 (0.60) 0.76 (0.67-0.83) |
|
Comparison between APS patients and controls |
|||||
|
Assay |
Area under the curve (95% Confidence interval) |
LR+/LR- at cut-off |
LR+/LR- at LR+ max |
Sensitivity (95% Confidence interval) |
Specificity (95% Confidence interval) |
|
D1 CIA |
0.89 (0.83-0.96) |
13.8/0.71 |
86.1 (75.9-93.1) |
91.1 (78.8-97.5) |
|
|
D1 ELISA |
0.83 (0.75-0.90) |
4.02/0.44 |
11.25/0.77 |
62.5 (50.3-73.6) |
84.4 (70.5-93.5) |
|
B2 ELISA (UK) |
0.90 (0.84-0.96) |
6.25/0.19 |
9.69/0.60 |
83.3 (72.7-91.1) |
86.7 (73.2-94.9) |
|
B2 ELISA (INOVA) |
0.93 (0.88-0.97) |
7.5/0.19 |
24.4/0.47 |
83.3 (72.7-91.1) |
88.9 (75.9-96.3) |
|
Discrimination between patients with and without history of thrombosis |
||||
|
|
D1 CIA |
D1 ELISA |
B2 ELISA (UK) |
B2 ELISA (INOVA) |
|
Sensitivity |
89.7 |
64.1 |
87.2 |
79.5 |
|
Specificity |
76.4 |
74.5 |
72.7 |
80.0 |
|
Likelihood ratio (+) |
3.80 |
2.52 |
3.20 |
3.97 |
|
Likelihood ratio (-) |
0.13 |
0.48 |
0.18 |
0.26 |
Conclusion:
Anti-β2GPI-D1 antibodies are a promising biomarker to aid in the diagnosis and risk assessment of APS patients. Confirmatory studies using multi-centric setups and large patient cohorts are necessary to confirm the data.
Disclosure:
R. Willis,
None;
M. Mahler,
Inova Diagnostics, Inc.,
3;
F. Pregnolato,
None;
C. Pericleous,
None;
A. Rahman,
None;
J. Ioannou,
None;
I. Giles,
None;
G. Lakos,
Inova Diagnostics, Inc.,
3;
R. Albesa,
Inova Diagnostics, Inc.,
3;
N. Zohoury,
Inova Diagnostics, Inc.,
3;
P. L. Meroni,
Inova Diagnostics, Inc.,
5;
S. S. Pierangeli,
None.
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