Frequent alanine aminotransferase flares and promising antiviral therapy efficacy during the preschool age: An opportunity to achieve HBsAg loss in children with mother-to-child transmitted hepatitis B.

Alanine aminotransferase (ALT) flare remains one of the determinants of initiating antiviral therapy in children with chronic hepatitis B (CHB). Insufficient data exist regarding children with CHB attributed to mother-to-child transmission. This study aimed to assess the occurrence of spontaneous ALT flares and identify factors affecting therapy-induced hepatitis B surface antigen (HBsAg) loss in the flare cohort. We retrospectively included untreated children with mother-to-child transmitted CHB. The primary outcomes were spontaneous ALT flares and therapy-induced HBsAg loss. Among 83 untreated children, 73.5% (61/83) experienced spontaneous ALT flares during the median follow-up of 14.6 months (range, 0.1-177.1 months), with 54.1% of the first ALT flares and 44.3% of ALT peaks occurring within 6 years of age. Thirty-six of 61 children with ALT flares received antiviral therapy, nine (25.0%) of whom achieved therapy-induced HBsAg loss with a median duration of 19.3 months (range, 6.5-56.2 months). The age of initiation of antiviral therapy was the sole predictor of therapy-induced HBsAg loss (HR = 0.544, 95% CI 0.353-0.838, p = 0.006). The restricted cubic spline showed a negative relationship between the age of initiation of antiviral therapy and HBsAg loss and identified that 6.2 years of age discriminated children with therapy-induced HBsAg loss. Kaplan-Meier estimations suggested a higher probability of HBsAg loss in children who started antiviral therapy before 6.2 years old (p = 0.03). In conclusion, asymptomatic ALT flares were frequent in preschool-aged children with mother-to-child transmitted CHB, and early initiation of antiviral therapy showed promising effects in those children with ALT flares.