Diagnostic performance of serological assays for anti-HBs testing: Results from a quality assessment program

Background: Post-vaccination testing after hepatitis B vaccination is indispensable to evaluate long-term immunological protection. Using a threshold level of antibodies against hepatitis B surface antigen (antiHB s) to define serological protection, implies reproducible and valid measurements of different diagnostic assays. Objectives: In this study we assess the performance of currently used anti-HBs assays. Study design: In 2013, 45 laboratories participated in an external quality assessment program using pooled anti-HBs serum samples around the cutoff values 10 IU/1 and 100 IU/1. Laboratories used either Axsym (Abbott Laboratories), Architect (Abbott Laboratories), Access (Beckman-Coulter), ADVIA Centaur anti-HBs2 (Siemens Healthcare Diagnostics), Elecsys, Modular or Cobas (Roche Diagnostics) or Vidas Total Quick (Biomerieux) for anti-HBs titre quantification. We analysed covariance using mixed-model repeated measures. To assess sensitivity/specificity and agreement, a true positive or true negative result was defined as an anti-HBs titre respectively above or below the cutoff value by >= 4 of 6 assays. Results: Different anti-HBs assays were associated with statistically significant (P<0.05) differences in anti-HBs titres in all dilutions. Sensitivity and specificity ranged respectively from 64%-100% and 95%100%. Agreement between assays around an anti-HBs titre cutoff value of 10 IU/1 ranged from 93%-100% and was 44% for a cutoff value of 100 IU/1. Conclusions: Around a cutoff value of 10 IU/1 use of the Access assay may result in false-negative results. Concerning the cutoff value of 100 IU/1, a sample being classified below or above this cutoff relied heavily on the specific assay used, with both the Architect and the Access resulting in false-negative results. (C) 2016 Elsevier B.V. All rights reserved.