PB0080 - Performance Of Chemiluminescence Assays for Laboratory Diagnosis of Antiphospholipid Syndrome – A Single Centre Experience

Sunday, June 23, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

EL

Eunice E. N. Lai

Senior Resident
Department of Haematology-Oncology, National University Hospital
Singapore, Singapore

Co-Author(s)

JL

Jacqueline Lau

Senior Medical Laboratory Scientist
Division of Haematology, Department of Laboratory Medicine, National University Hospital
Singapore, Singapore
Eng Soo Yap, MBBS MMed

Senior Consultant
Division of Haematology, Department of Laboratory Medicine, National University Hospital
Singapore, Singapore
YC

Yen Lin Chee

Senior consultant
Division of Hematology, Department of Haematology-Oncology, National University Cancer Institute, Singapore
Singapore, Singapore
CL

Cheryl XQ Lim

Consultant
Department of Haematology-Oncology, National University Hospital
Singapore, Singapore
SC

Stephrene S. W. Chan

Consultant
Department of Haematology-Oncology, National University Hospital
Singapore, Singapore
WT

Winnie Z.Y. Teo

Consultant
Department of Haematology-Oncology, National University Hospital
Singapore, Singapore
SL

Shir Ying Lee

Senior Consultant
Department of Haematology-Oncology, National University Hospital
Singapore, Singapore

Background: Detection of antiphospholipid antibodies (aPL) is required for the diagnosis of antiphospholipid syndrome (APS). Enzyme-linked immunoassay (ELISA) is the standard method for aPL. The chemiluminescence assay (CLIA) is an alternative method that is fully automated and less labour-intensive.

Aims: A qualitative and quantitative comparison between the ELISA and CLIA methods for the detection of aPL. To evaluate the relationship between aPL detected by each method to clinically relevant outcomes.

Methods: Patient samples were concurrently tested with the ELISA (QUANTA LiteTM) and CLIA (ACL AcuStarTM) for anti-cardiolipin antibody (ACA) and anti-B2-glycoprotein-1 (B2GPI) IgG and IgM. Clinical data including the presence of revised Sapporo APS clinical criteria were extracted. Data collection was approved by the institution’s review board.

Results: 107 patients were included. 63% were female, median age was 48 years and 67% had any Sapporo clinical criteria fulfilled (66 had thrombotic and 9 had obstetric criteria). 22 patients had APS (15 primary and 7 secondary).

ELISA and CLIA showed above 75% concordance rates for ACA-IgG, ACA-IgM and B2GPI-IgM, with good correlation between ELISA titres and CLIA units (r coefficient 0.60-0.80, p< 0.0001). Receiver operating characteristics of CLIA showed an area under the curve (AUROC) of 0.8-0.9. However, for B2GPI-IgG, concordance rate was only 36.67%, with no correlation between the ELISA titre and CLIA units (r = 0.06, p=0.746; AUROC 0.5).

There was no statistically significant difference in the occurrence of any Sapporo APS clinical criteria (thrombosis and obstetric combined), or the occurrence of venous and arterial thrombosis in the ELISA-positive versus the CLIA-positive group.

Conclusion(s): CLIA showed acceptable performance characteristics for ACA-IgG, ACA-IgM and B2GPI-IgM compared with ELISA. However, the concordance of B2GPI-IgG CLIA with ELISA was poor. Physicians should be aware of possible discrepant B2GPI-IgG results with the two methods which may result in different classification of APS.