title: Risk factors of isolated antibody against core antigen of hepatitis B virus: association with HIV infection and age but not hepatitis C virus infection.
abstract: BACKGROUND
  Isolated antibody to hepatitis B core antigen (anti-HBc) is defined as seropositivity for anti-HBc in the absence of hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). It is commonly found in HIV-infected persons or hepatitis C virus (HCV)-infected persons, but the risk factors for isolated anti-HBc remain uncertain, especially in regions that are hyperendemic for hepatitis B virus (HBV) infection.
  
  
  METHODS
  This cross-sectional study included a cohort of 955 nonhemophiliac, HIV-infected patients, diagnosed between 1988 and 2009, and 643 HIV-uninfected injection drug users (IDUs) attending the methadone clinic between August 2007 and May 2009, with available HBV serological data. The medical records were reviewed to identify the risk factors associated with seropositivity of isolated anti-HBc.
  
  
  RESULTS
  The overall seroprevalence of isolated anti-HBc was 12.1% (193 of 1598), in which occult HBV infection accounted for 1.6% (3 of 185) and the majority (91.2 %, 176 of 193) had low titers of anti-HBs (3.6 +/- 2.9 IU/L). Subjects with isolated anti-HBc were significantly older (40.7 +/- 9.3 versus 36.9 +/- 8.0, respectively, P < 0.0001). There was a significantly increasing trend in the prevalence of isolated anti-HBc with age, from 4.0% in those younger than 30 years to 22.5% after 50 years of age (test for trend, P < 0.0001). A significantly higher prevalence of isolated anti-HBc was observed in HIV-infected subjects [14.0% (134 of 955) versus 9.2% (59 of 643), adjusted odds ratio, 1.64; P < 0.01], but not in those with HCV infection (P = 0.18).
  
  
  CONCLUSIONS
  Isolated anti-HBc seropositivity was significantly associated with HIV infection, and older age. HCV infection was not associated with isolated anti-HBc in a country hyperendemic with HBV infection, even in populations with a high prevalence of HCV infection. The majority was not attributable to occult HBV infection, but rather, low level of anti-HBs, suggesting that HBV vaccination may not be required.
authors.affiliation: Department of Medicine, E-Da Hospital/I-Shou University, Kaohsiung County, Taiwan.
authors.forename: Shiou-Haur
authors.initials: SH
authors.lastname: Liang
authors.forename: Tai-Jui
authors.initials: TJ
authors.lastname: Chen
authors.forename: Susan Shin-Jung
authors.initials: SS
authors.lastname: Lee
authors.forename: Fan-Chen
authors.initials: FC
authors.lastname: Tseng
authors.forename: Chun-Kai
authors.initials: CK
authors.lastname: Huang
authors.forename: Chung-Hsu
authors.initials: CH
authors.lastname: Lai
authors.forename: Chou-Ping
authors.initials: CP
authors.lastname: Chiou
authors.forename: Jiun-Ling
authors.initials: JL
authors.lastname: Wang
authors.forename: Hsing-Chun
authors.initials: HC
authors.lastname: Chung
authors.forename: Jiun-Nong
authors.initials: JN
authors.lastname: Lin
authors.forename: Yi-Chi
authors.initials: YC
authors.lastname: Kuo
authors.forename: Hsi-Hsun
authors.initials: HH
authors.lastname: Lin
mesh_terms: D000328:Adult; D000367:Age Factors; D018791:CD4 Lymphocyte Count; D003430:Cross-Sectional Studies; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000276:immunology / Q000821:virology; D015497:HIV-1; D006509:Hepatitis B / Q000150:complications* / Q000276:immunology / Q000821:virology; D006512:Hepatitis B Core Antigens / Q000097:blood*; D006526:Hepatitis C / Q000150:complications* / Q000276:immunology / Q000821:virology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D016036:Seroepidemiologic Studies
chemical_list: D006512:Hepatitis B Core Antigens