Favourable Prognosis of Patients With Untreated HBeAg-Negative Chronic Hepatitis B Virus Infection With HBsAg < 100 IU/mL

Background: Serum hepatitis B surface antigen (HBsAg) < 100 IU/mL has been recently proposed as one of the key criteria of 'partial cure' in patients with chronic hepatitis B virus (HBV) infection. We analysed the clinical prognosis of hepatitis B e antigen (HBeAg)-negative untreated patients with HBsAg < 100 IU/mL and normal alanine aminotransferase (ALT) levels.

Methods: Five hundred and twenty-one untreated patients with HBeAg negativity, HBsAg < 100 IU/mL and normal ALT levels were included from three hospitals. Spontaneous HBsAg seroclearance, phase transition, liver fibrosis progression and hepatocellular carcinoma (HCC) development were analysed.

Results: The median age was 43.0 years, and 62.2% of the patients were male. After a median follow-up of 25.0 months, 52 (10.0%) patients achieved spontaneous HBsAg seroclearance. The annual HBsAg seroclearance rate is 4.2%. Patients with baseline HBsAg ≤ 10 IU/mL (adjusted hazard ratio [aHR] = 3.490, p < 0.001) and male sex (aHR = 1.980, p = 0.041) were more likely to achieve HBsAg seroclearance. Only 4 (0.8%) and 23 (4.8%) patients transitioned to the immune escape phase and HBeAg-negative indeterminate phase, respectively. Baseline serum HBsAg > 10 IU/mL (aHR = 3.846, p = 0.034) and detectable HBV DNA (aHR = 2.672, p = 0.023) were associated with transition to the HBeAg-negative indeterminate phase. No patient developed HCC or had fatal outcomes.

Conclusions: HBeAg-negative patients with serum HBsAg < 100 IU/mL and normal ALT levels had a favourable prognosis. HBsAg ≤ 10 IU/mL and male sex were associated with a higher rate of HBsAg seroclearance, while HBsAg > 10 IU/mL and detectable HBV DNA were associated with a higher risk of transition to the indeterminate phase.