Positive hepatitis B virus core antibody in HIV infection--false positive or evidence of previous infection?

Isolated HBV core antibody (anti-HBc) is defined as the presence of anti-HBc with a negative HBV surface antigen (HBsAg) and HBV surface antibody (anti-HBs <10 IU/l). In patients infected with HIV with isolated anti-HBc, the aim was to determine: The prevalence of isolated positive anti-HBc; The most effective method of identifying which patients have had previous Hepatitis B Virus (HBV) infection; The prevalence of false positive anti-HBc. HBV serology results were identified from 539 patients infected with HIV sampled between January 2010 and December 2012. In those with an isolated anti-HBc and negative anti-HBe, a second anti-HBc test was carried out using a different assay. Samples were also screened for HBV DNA. The anti-retroviral regimens at time of screening were documented. 101/539 had an isolated anti-HBc. Of these, 32 (32%) had a positive anti-HBe (including 1 equivocal) and 69(68%) were anti-HBe negative. Of those negative for anti-HBe, 32 were tested for both DNA and a second anti-HBc. Of these 26 (81%) were on cART at time of HBV testing, with 25 (78%) on ART with anti-HBV activity. The prevalence of isolated anti-HBc was 19%. Only 32% were also anti-HBe positive, whereas 97% of those anti-HBe negative were positive on a second anti-HBc assay suggesting lack of utility of anti-HBe in resolving serological quandaries. One subject (3%) had a false positive anti-HBc. There was no evidence of chronic HBV but 78% patients were on HBV-suppressive combination anti-retroviral therapy.