The Role of Quantitative HBsAg Levels in Chronic Hepatitis B

Introduction: Chronic hepatitis B (CHB) infection is essential for patient management, including treatment and follow-up. Therefore, quantitative hepatitis B surface antigen (qHBsAg) may help physicians identify the stages of hepatitis B virus (HBV) infection. This study aimed to examine the variance in qHBsAg levels across various stages of viral infection. Methods: This cross-sectional study, 183 patients who attended the Infectious Diseases outpatient clinic at Haseki Training and Research Hospital between July and December 2020, tested positive for HBsAg, and did not undergo prior treatment. Results: Among the 183 patients, 54.1% were male. The mean qHBsAg level was 2,155 IU/mL (interquartile range: 625-12,759). Correlation analysis revealed that qHBsAg was significantly associated with age, laboratory results, and HBV-DNA. In the receiver operating characteristic analysis, which evaluates the predictive power of qHBsAg for chronic hepatitis, the area under the curve was 0.749, and the optimal cut-off value for qHBsAg was 3,081 IU/mL. The cutoff value for the 95% specificity of qHBsAg in predicting chronic hepatitis was 38,641 IU/mL. Conclusion: Quantitative HBsAg is an easily applicable and relatively inexpensive test for distinguishing different stages of chronic hepatitis. Therefore, qHBsAg can help clinicians assess liver injury and plan treatment at the most appropriate time for patients with CHB infection. In patients with HBV-DNA levels exceeding 2,000 IU/mL, commencement of treatment without the necessity of liver biopsy may be considered when the qHBsAg exceeds 38,000 IU/mL.