Comparative evaluation of CLIA and EIA for Quantiferon-TB Gold Plus.

The purpose of this study was to compare the Quantiferon-TB Gold Plus test analysed with chemiluminescence immunoassay (CLIA) to immunoassay (EIA). One hundred and twenty-five clinical specimens submitted to Karolinska University Hospital for Quantiferon-TB Gold Plus analysis were used to analyse agreement of the CLIA and EIA assays. The imprecision on CLIA was determined by analysis of pooled clinical samples of antigen tubes (TB1 and TB2), a reference material from National Institute for Biological Standards and Control (NIBSC 82/587) and two controls of the test. Recovery on CLIA was determined by analysis of the TB1 and TB2 samples and NIBSC 82/587. Concordant results were obtained for 110 (88.0%) of 125 samples with cut-off including a borderline range. With no borderline range, 121 of 125 samples (96.8%) showed concordant results. Repeatability had a coefficient of variation (CV) of 14.9%. Reproducibility for pooled clinical samples TB1 and TB2 had a CV of 10.5% and 11.0%, respectively, and for the NIBSC 82/587 7.45%, and kit controls 31.0% respective 12.2%. Overall recovery had a mean of 94.1% (SD 12%). We concluded that Quantiferon-TB Gold Plus analysed with the CLIA assay shows good concordance with EIA and acceptable imprecision.