Abstract
BACKGROUND & AIMS: Most patients in the immunotolerant (IT) phase of chronic hepatitis B (CHB) transition to the immune active (IA-hepatitis B surface antigen [HBeAg]+) phase by early adulthood. We examined characteristics of adults in the IT vs IA-HBeAg+ phase and rate of transition from IT to other phases of CHB, with a focus on those ≥40 years. METHODS: Demographic, clinical, and virologic characteristics of participants in the Hepatitis B Research Network adult cohort study with IT CHB (alanine aminotransferase ≤1.5 × upper limit of normal, hepatitis B virus DNA >10(7) IU/mL) were compared by age category, and to those with IA-HBeAg+ CHB in cross-sectional analysis. This study received institutional review board approval at all participating centers. RESULTS: Of 107 adult IT participants, 52 (48%) were <30, 33 (31%) were 30 to 39, and 22 (21%) were ≥40 years old (maximum, 71 years). Among IT groups, the proportion born in Asia and duration of CHB were greater in older IT groups, but virologic and liver disease characteristics were similar. Compared with IA-HBeAg+ participants (n = 192), IT participants were younger, fewer were men, more were Asian, and platelets, qHBsAg, and qHBeAg levels were higher. Similar differences were observed when comparisons were made with the ≥40 years IT group. Among IT participants, 60 (56%) transitioned during 206 person-years of follow-up. The phase transition rate per 100 person-years was highest in the <30 years group (33.0 [95% confidence interval [CI], 23.4-46.7]) vs the 30 to 39 years group (24.8 [95% CI, 15.6-39.4]) and ≥40 group (27.4 [95% CI, 14.8-50.9]), but 95% CIs overlapped. CONCLUSIONS: In a large North American population, over 50% of adults in the IT phase of CHB were ≥30 years and 20% were ≥40 years old, but older IT patients had similar characteristics and rates of transition as younger IT patients.