SummaryBackground and aimDistinguishing inactive hepatitis B surface antigen (HBsAg) carriers from hepatitis B e antigen-negative hepatitis remains difficult but is important because patients with active hepatitis may develop severe complications. Long-term follow-up data with stringent criteria are required for the identification of inactive HBsAg carriers. A single serum HBsAg level may be used to solve this difficult diagnostic issue; however, very few studies on its application in older patients have been published. This study was designed to evaluate the clinical significance of a single serum HBsAg level in older patients with chronic hepatitis B (CHB).Materials and methodsFrom January 2012 to December 2012, the clinical manifestations of 1749 HBsAg-positive patients were analyzed including 412 patients aged ≥ 60 years (mean age at enrollment, 68.6 ± 6.9 years; range, 60–90 years; 262 males and 150 females). We investigated the possibility of using a single serum HBsAg level to predict cirrhosis and hepatocellular carcinoma (HCC) in older patients with CHB.ResultsOf the 1749 HBsAg-positive patients, those aged ≥ 60 years tended to have lower serum HBsAg levels than the younger patients. In fact, all patients aged ≥ 60 years had a serum HBsAg level ≤ 10,000IU/mL. Of the 412 patients aged ≥ 60 years, 122 (29.6%) had cirrhosis and 59 (14.3%) developed HCC. When an HBsAg-titer < 100IU/mL was used to examine severe clinical outcomes (cirrhosis or HCC), the sensitivity, specificity, positive predictive value, and negative predictive value for being free of liver cirrhosis and HCC were 49.3% and 95.2%, 19.7% and 28.8%, 85.6% and 95.2%, and 40.0% and 71.2%, respectively.ConclusionA single serum HBsAg level < 100IU/mL might predict favorable clinical results in older patients with late-stage CHB virus infection.