Application Study of Neutralization Confirmatory Testing for Low Positive Hepatitis B Surface Antigen

Area of Science:

• Hepatology
• Clinical Chemistry
• Immunodiagnostics

Background:

• High sensitivity of HBsAg quantitative tests presents challenges in interpreting weakly positive results.
• Accurate interpretation of low positive hepatitis B surface antigen (HBsAg) is crucial for patient management.
• Clinical utility of neutralization confirmatory testing for low positive HBsAg requires further exploration.

Purpose of the Study:

• To explore the clinical utility of neutralization confirmatory testing for specimens with low positive HBsAg.
• To evaluate the effectiveness of neutralization testing in confirming HBsAg presence.
• To determine the optimal cutoff for HBsAg levels using neutralization confirmatory testing.

Main Methods:

• Retrospective analysis of 382 outpatient and inpatient cases from January 2021 to January 2022.
• Reanalysis of low positive HBsAg samples using chemiluminescence microparticle immunoassay (CMIA), confirmatory testing, and enzyme-linked immunosorbent assay (ELISA).
• Analysis of hepatitis B serum markers (e-antigen, e-antibody, core antibody) and receiver operating characteristic (ROC) analysis.

Main Results:

• Confirmatory testing showed a 34.5% positivity rate for HBsAg values between 0.05-0.09 IU/mL, with true positives from 0.07-0.09 IU/mL.
• For HBsAg values between 0.10-0.49 IU/mL, confirmatory testing yielded a 96.1% positivity rate.
• ROC analysis indicated an optimal sensitivity and specificity at 0.14 IU/mL; 100% positivity in e-antigen-positive and 93.8% in e-antigen-negative groups.

Conclusions:

• Neutralization confirmatory testing is effective for confirming weakly positive, low-value HBsAg specimens.
• The optimal cutoff for HBsAg level, using neutralization confirmatory testing, is determined to be 0.14 IU/mL.
• This testing serves as a valuable tool for accurate HBsAg interpretation in clinical practice.