Background:
Quantifying hepatitis B virus (HBV) DNA is the main laboratory test for diagnosis and monitoring of patients with chronic HBV infection (CHB). Such assays are molecular-based and often expensive for health systems worldwide. Measure of HBV surface antigen (HBsAg) levels by automated chemiluminescent immunoassay (CLIA) has been proposed as a surrogate and cost-effective marker that may simplify HBV management. In this study, we determined whether quantitative HBsAg levels correlate with HBV-DNA levels in a cohort of CHB patients.

Material and methods:
This cross-sectional study was performed in the Laboratory of Virology, ‘‘St. Marina’’ University Hospital, Varna, Bulgaria, from January 2022 to December 2024. In total, 315 serum samples from CHB patients were obtained, and HBsAg, HBV-DNA and HBV early antigen (HBeAg)/anti-HBe levels were measured.

Results:
The Spearman’s rank correlation between the HBsAg and HBV-DNA in the entire sample was 0.51 with a p-value <0.001. In the HBeAg-negative patients, the correlation coefficient was 0.49, and in HBeAg-positive – 0.49 (both p-values <0.001).

Conclusions:
HBsAg levels, measured by chemiluminescence assay, moderately correlated with HBV-DNA levels in CHB patients from Varna, Bulgaria. The correlation’s strength was not related to the individuals’ HBeAg status.