Analysis of the antiphospholipid antibodies testing results from College of American Pathologists proficiency testing

Abstract

Objective To analyze our antiphospholipid antibodies (aPLs) testing results from College of American Pathologists (CAP) proficiency testing (PT) from January 2009 to December 2016, in order to continuously improve the detection of aPLs items in the monitoring laboratory. Methods The retrospective analysis was used. From January 2009 to December 2016, the laboratory of Rheumatology of Peking Union Medical College Hospital received 2 batches of 3 samples per year through mail, Enzyme linked immunosorbent assay (ELISA) was used to detect anticardiolipin (aCL) and anti-β2-glycoprotein 1 (aβ2GP1) within 10 days and the results were reported to CAP for evaluating. Results The laboratory took part in the CAP aPLs project PT activities for 16 times and obtained a total of 96 results. All the results were acceptable and the total PT score was 100%. The number of participates increased annually. Compared with the first PT in 2009, the number of laboratories participating in aCL-IgG PT, aCL-IgM PT aCL-IgA PT, aβ2GP1-IgG PT, aβ2GP1-IgM PT and aβ2GP1-IgA PT increased by 24.55%, 24.53%, 20.13%,179.73%, 197.01% and 151.16% respectively in 2016. The detection method has gradually changed from a single ELISA method into a variety of methodologies, including ELISA, chemiluminescent immunoassay (CLIA), fluorescence enzyme immunoassay (FEIA) and liquid chip technology (xMAP Technology). The world return results showed good consistencies (more than 90%) in both the high-titer positive results and negative results, but the consistencies of the test results of the low-and medium-titer positive samples were poor. Conclusions Our aPLs results reach CAP′s quality verification requirement. Although more and more laboratories around the world pay attention to the external quality assessment of the aPLs project, but the quality of the detection of aPLs samples with weak positive to medium intensity remains to be improved. Key words: Antiphospholipid antibodies; Proficiency testing; Quality control