Age of hepatitis B e antigen loss in Aboriginal, Torres Strait Islander and non-Indigenous residents of tropical Australia; implications for clinical care.

Abstract: This study determined the hepatitis B e antigen (HBeAg) status of people living with chronic hepatitis B (CHB) in Far North Queensland (FNQ), Australia and their age of HBeAg loss. It was hoped that this would provide data to explain the stark difference in the incidence of hepatocellular carcinoma (HCC) between Aboriginal and Torres Strait Islander individuals living with CHB in FNQ, a finding that has been hypothesised to relate to differences in hepatitis B virus genotype. We identified every FNQ resident with CHB, determined their country of birth, their HBeAg status, the age they lost HBeAg and whether they identified as an Aboriginal, a Torres Strait Islander or a non-Indigenous individual. We then ascertained whether these demographic and virological variables were correlated. Of 1,474 individuals living with CHB in FNQ, 278 (19%) were Aboriginal, 507 (34%) were Torres Strait Islanders and 689 (47%) were non-Indigenous. Aboriginal individuals were less likely to be HBeAg positive (26/278, 9%) than Torres Strait Islander (91/507, 18%) and non-Indigenous (126/689, 18%) individuals, p < 0.0001. Aboriginal individuals lost HBeAg at an earlier age (median (interquartile range): 30 (23-39) years) than Torres Strait Islander (38 (29-49) years) and non-Indigenous (36 (29-47) years) individuals, p < 0.0001. Aboriginal individuals with CHB in FNQ are more likely to be HBeAg negative than Torres Strait Islander and non-Indigenous individuals and lose HBeAg at a younger age. This provides a biological basis for local clinicians' observation that Aboriginal individuals with CHB in FNQ are at a lower risk of HCC and data to support the principle of genotype-based care in the region.