Resolving Uncertainty in Hepatitis B Diagnosis: Evaluating Neutralization Testing for Borderline HBsAg

Son, Beom Se
Yoo, Jaeeun

Department of Laboratory Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea

Address correspondence to Jaeeun Yoo; Department of Laboratory Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsu-ro, Bupyeong-gu, Incheon 21431, Korea; phone: +82 32 280 5484; fax: +82 32 280 5520; e mail: [email protected]

Annals of Clinical & Laboratory Science 55(3):p 404-408, May-June 2025.

Abstract.

Objective.

To assess the performance of neutralization confirmatory testing for borderline hepatitis B surface antigen (HBsAg) results (signal-to-cutoff [S/CO] 1.0-10.0) in a low-prevalence population.

Method.

We retrospectively analyzed 115 borderline-reactive HBsAg samples from asymptomatic adults with normal liver enzyme levels. Screening was performed using the Abbott Alinity i assay, followed by confirmatory testing with the Abbott HBsAg Confirmatory Reagent. A ≥50% signal reduction was required for confirmation.

Results.

Among 115 borderline samples, 61 (53.0%) were confirmed by neutralization testing. Confirmation rates increased with higher S/CO values: 31.6% (1.0-2.0), 57.1% (2.1-5.0), and 75.0% (5.1-10.0). The median S/CO values were 1.5 (1.0-2.0), 3.4 (2.1-5.0), and 7.2 (5.1-10.0) for each subrange. Logistic regression showed a significant correlation between higher S/CO values and confirmation (odds ratio 1.42 per unit increase, p<0.001). Notably, most unconfirmed cases had S/CO values below 3.0, suggesting frequent false reactivity in low-positive samples.

Conclusion.

Lower borderline HBsAg results often reflect nonspecific assay reactivity, emphasizing the need for confirmatory testing to prevent misdiagnosis. Higher S/CO values were strongly associated with true HBsAg positivity, supporting the use of neutralization testing in routine practice.