A multi-centre evaluation of the intra-assay and inter-assay variation of commercial and in-house anti-cardiolipin antibody assays.
OBJECTIVE
To assess the intra-assay (intra-run) and inter-assay (inter-run) variation of commercial and in-house IgG and IgM anti-cardiolipin antibody (aCL) assays/kits, and to determine an appropriate maximum value for inclusion in consensus guidelines.


METHODS
Frozen aliquots of two patient specimens and one commercial control were sent to nine laboratories for the evaluation of eight commercial kits and one in-house assay. Intra-assay and inter-assay evaluations were performed with all three samples for IgG aCL, and one patient specimen for IgM aCL.


RESULTS
The IgG and IgM aCL values varied considerably between the nine assays/kits. The majority of assays/kits demonstrated less than 20% intra-assay and inter-assay variation, with lower intra-assay and inter-assay variation observed with the commercial control. Single calibrator assays were not consistently associated with higher inter-assay variation than multi-point calibrator assays.


CONCLUSIONS
An inter-assay coefficient of variation of 20% was determined to be an appropriate maximum value for inclusion in the Australasian aCL Working Party consensus guidelines. Improved standardisation between different assay/kits is still required.
Wong
Richard
R
Division of Immunology, Queensland Health Pathology Services, Princess Alexandra and Royal Brisbane Hospitals, Qld, Australia. richard_wong@health.qld.gov.au
Favaloro
Emmanuel
E
Pollock
Wendy
W
Wilson
Robert
R
Hendle
Michelle
M
Adelstein
Stephen
S
Baumgart
Karl
K
Homes
Paul
P
Smith
Stuart
S
Steele
Richard
R
Sturgess
Allan
A
Gillis
David
D
D017153:Antibodies, Anticardiolipin / Q000032:analysis*; D001315:Australia; D019411:Clinical Laboratory Techniques / Q000592:standards*; D032921:Consensus; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007753:Laboratories / Q000592:standards*; D011785:Quality Assurance, Health Care; D011933:Reagent Kits, Diagnostic / Q000592:standards*; D015203:Reproducibility of Results
D017153:Antibodies, Anticardiolipin; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011933:Reagent Kits, Diagnostic