A Multilaboratory Peer Assessment Quality Assurance Program-Based Evaluation of Anticardiolipin Antibody, and beta2-Glycoprotein I Antibody Testing

Emmanuel J. Favaloro; Richard C. W. Wong; Roger Silvestrini; Robert McEvoy; Susan Jovanovich; Peter Roberts-Thomson

doi:10.1055/s-2005-863808

Seminars in Thrombosis and Hemostasis, Table of Contents

Semin Thromb Hemost 2005; 31(1): 73-84
DOI: 10.1055/s-2005-863808

A Multilaboratory Peer Assessment Quality Assurance Program-Based Evaluation of Anticardiolipin Antibody, and beta₂-Glycoprotein I Antibody Testing

Emmanuel J. Favaloro¹ ^, ² , Richard C. W. Wong⁴ , Roger Silvestrini³ , Robert McEvoy⁵ , Susan Jovanovich⁵ , Peter Roberts-Thomson⁵

¹Senior Scientist in Charge, Haemostasis Laboratories, Departments of Haematology and Immunopathology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Walls, Australia
²Department of Haematology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Walls, Australia
³Department Immunopathology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Walls, Australia
⁴Division of Immunology, Queensland Health Pathology Services, Princess Alexandra & Royal Brisbane Hospitals, Brisbane, Australia
⁵Royal College of Pathologists of Australasia Quality Assurance Program Pty Ltd, Flinders Medical Centre, Adelaide, Australia

Abstract

ABSTRACT

We evaluated the performance of anticardiolipin (aCL) and beta₂-glycoprotein I (β₂-GPI) antibody assays through a large external quality assurance program. Data from the 2002 cycle of the Royal College of Pathologists of Australasia Quality Assurance Program (RCPA QAP) were analyzed for variation in reported numerical values and semiquantitative results or interpretations according to method type or group and in conjunction with available clinical data. High interlaboratory variation in numerical results and notable method-based variation, combined with a general lack of consensus in semiquantitative reporting, continues to be observed. Numerical results from cross-laboratory testing of 12 serum samples (for immunoglobulin G [IgG]-aCL, IgM-aCL, and IgG-β₂-GPI) yielded interlaboratory coefficients of variation (CVs) that were higher than 50% in six of 12 (50%) specimens for IgG-aCL, and 12 of 12 (100%) specimens for IgM-aCL and IgG-β₂-GPI. Semiquantitative reporting also varied considerably, with total (100%) consensus occurring in only four of 36 (11%) occasions. General consensus (where > 90% of participating laboratories agreed that a given serum sample gave a result of either negative or positive) was only obtained on 13 of 36 (36%) occasions. Variation in results between different method types or groups were also present, resulting in potential biasing of the RCPA QAP-defined target results by the large number of laboratories using the dominant aCL assays. Finally, laboratory findings frequently did not agree with the available clinical information. In conclusion, in a large proportion of specimens from the 2002 RCPA QAP cycle, laboratories could not agree on whether a serum sample tested was aCL-positive or aCL-negative, or β₂-GPI-positive or β₂-GPI-negative. Despite prior attempts to improve the standardization of testing and reporting practices, laboratory testing for aCL and anti-β₂-GPI still demonstrates significant interlaboratory and intermethod variation, which needs to be taken into account for the clinical interpretation of test results, especially those from different laboratories.

KEYWORDS

Anticardiolipin antibody - antiphospholipid antibody - assays - laboratory assessment - quality assurance - antiphospholipid syndrome

Full Text

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Dr.
E. J FavaloroPh.D.

Department of Haematology, Institute of Clinical Pathology and Medical Research (ICPMR)

WSAHS, Westmead, New South Walls, 2145, Australia

Email: emmanuel@icpmr.wsahs.nsw.gov.au