Prevalence and influential factors of isolated hepatitis B core antibody positivity in a Chinese adult population.

Isolated anti-HBc (IAHBc) is defined by the presence of anti-HBc in the absence of HBsAg and hepatitis B surface antibody (anti-HBs). IAHBc is of great clinical significance as a specific pattern of HBV infection, but IAHBc has not been fully clarified. This study aimed to explore the prevalence and influential factors of IAHBc from routine examination results of inpatients.A total of 61,247 individuals were included in the study, with a median age of 55 years (range: 43-68), and a male-to-female ratio of 0.90:1. The prevalence of current HBV infection (HBsAg positive) was 6.82%, while the prevalence of previous HBV infection (HBsAg negative but anti-HBc positive) was 48.63%. The prevalence of IAHBc was 12.31%. Among them, the rates for males were 7.10%, 52.16%, and 13.70%, respectively, which were significantly higher than the rates for females at 6.56%, 45.45%, and 11.06% (P < 0.05). The prevalence rates mentioned above were significantly reduced after vaccination (P < 0.05). The prevalence of IAHBc increases with age, rising from 0.23% in the age group of 15-29 years to 13.57% in individuals aged 80 and above. After the age of 50, the prevalence of IAHBc closely parallels the previous infection rate but shows no significant association with the current infection rate (P > 0.05). Among IAHBc individuals, approximately 33.83% tested positive for anti-HBe, and their anti-HBc absorbance values were significantly higher compared to anti-HBe negative individuals (7.08 and 5.31, P < 0.01). The prevalence of anti-HBe positivity among IAHBc individuals does not vary with changes in the previous infection rate and age (P > 0.05).