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

Biotin interferences: Have we neglected the impact on serological markers?

BACKGROUND

Biotin has been reported to be a leading cause of interference on several immunoassay platforms using the streptavidin-biotin immobilization system. While biotin interferences have now been well characterized for several assays, only few data are available on their impact on serological markers of infectious viral diseases.

METHODS

Overall, 10 healthy volunteers (HVs) received a single 100 mg dose of biotin to evaluate its effect on hepatitis B serological markers. Blood samples were taken several times before and after biotin intake. In addition, spiking experiments were applied to investigate biotin's impact on anti-HIV/p24 Ag and anti-HCV antibody levels. Several procedures designed to overcome this interference were evaluated.

RESULTS

Biotin intake resulted in a false-negative anti-HBs immunological status (<10 mIU/mL) in 40.0% of cases. According to our anti-HBc and anti-HBe results, biotin intake was associated with 90.0% and 80.0% of false positive results, respectively. At the theoretical biotin peak concentration following a 100 mg intake, 50.0% and 66.6% of anti-HIV and anti-HCV results were false negatives, respectively. All the procedures evaluated to overcome the interference were proven effective.

CONCLUSION

HBV, HCV, and HIV serological markers are likely to be highly sensitive to biotin. Our data confirm that the scope of biotin interference is broader than commonly described.

Performance evaluation of the re-standardized Abbott Architect anti-HBs assay

BACKGROUND

As defined by World Health Organization (WHO), an antibody level of ≥ 10mIU/mL to hepatitis B virus confers protection. With the launching of Abbott anti-HBs assay re-standardized to the 2^nd WHO International Reference Preparation, a positive bias in antibody level would be anticipated. Manufacturer provides limited data for samples around the immune cut-off which has potential implication on vaccine guidance.

OBJECTIVES

To evaluate the performance of the re-standardized Abbott Architect anti-HBs assay and to determine the impact of the upward shift.

STUDY DESIGN

A total of 52 samples, including 12 external quality assurance programme samples and 40 clinical samples were tested with both the Abbott 1^st WHO standardized and the 2^nd WHO re-standardized assay and results compared. The 2^nd WHO anti-HBs standard and Acometrix anti-HBs control were also included for comparison.

RESULTS

Verification of the re-standardized assay with the 2^nd WHO anti-HBs standard revealed positive bias with mean closer to target value. Overall, the positive bias introduced by the new assay will only affect interpretation of samples with anti-HBs levels > 5.00 to < 10.00 mIU/mL previously tested on the Abbott 1^st WHO standardized anti-HBs assay.

CONCLUSIONS

Final interpretation of immune status to hepatitis B was not affected by the upward shift following introduction of the new Abbott anti-HBs assay except for previously negative samples with anti-HBs levels between >5.00 to <10.00 mIU/mL.

The quest for equivalence of test results: the pilgrimage of the Dutch Calibration 2.000 program for metrological traceability

Calibration 2.000 was initiated 20 years ago for standardization and harmonization of medical tests. The program also intended to evaluate adequate implementation of the In Vitro Diagnostics (IVD) 98/79/EC directive, in order to ensure that medical tests are fit-for-clinical purpose. The Calibration 2.000 initiative led to ongoing verification of test standardization and harmonization in the Netherlands using commutable external quality assessment (EQA)-tools and a type 1 EQA-design, where feasible. National support was guaranteed by involving all laboratory professionals as well as laboratory technicians responsible for EQA and quality officers. A category 1 EQA-system for general chemistry analytes, harmonizers for specific analytes like hGH and IGF-1, and commutable materials for other EQA-sections have been developed and structurally introduced in the EQA-schemes. The type 1 EQA-design facilitates the dialogue between individual specialists in laboratory medicine and the IVD-industry to reduce lot-to-lot variation and to improve standardization. In such a way, Calibration 2.000 sheds light on the metrological traceability challenges that we are facing and helps the laboratory community to get the issues on the table and resolved. The need for commutable trueness verifiers and/or harmonizers for other medical tests is now seen as paramount. Much knowledge is present in the Netherlands and for general chemistry, humoral immunology and protein chemistry, a few endocrinology tests, and various therapeutic drug monitoring (TDM) tests, commutable materials are available. Also the multi sample evaluation scoring system (MUSE) and the category 1 EQA-design offer many possibilities for permanent education of laboratory professionals to further improve the between and within laboratory variation and the test equivalence.

Performance of rapid diagnostic tests for the detection of anti-HBs in various patient populations

BACKGROUND

Rapid diagnostic tests (RDTs) represent an attractive alternative method to conventional diagnosis of hepatitis B virus (HBV) infection.

OBJECTIVE

The aim of the present study was to evaluate the diagnostic performance of commercially available RDTs for the detection of anti-HBs in various patient populations.

STUDY DESIGN

A total of 347 individuals, 198 positive and 149 negative for anti-HBs, were studied.

RESULTS

The specificity of RDT detection of anti-HBs in serum was 98.0%, 96.0% and 97.3% with TOYO® HBsAb Test, QuickProfile™ HBsAb test and QuickProfile™ HBV-3 Panel test, respectively. The diagnostic sensitivity varied between 60.4% and 69.5%. The sensitivity of the three RDTs was markedly better when testing serum samples with an anti-HBs titer higher than 100IU/L, and reached 90% or more for an anti-HBs titer above 150IU/L.

CONCLUSIONS

This performance was disappointing because the assays were not sensitive enough to detect low antibody titers. Thus, these tests require further improvement before they can be widely used in clinical practice.