title: Impact of a policy to permit the return of donors repeat-reactive to the Abbott PRISM antibody to hepatitis B core antigen assay.
abstract: BACKGROUND
  The expected donor loss from recent implementation of antibody to hepatitis B core antigen (anti-HBc) testing in Canada was uncertain but potentially significant based on US experience. To reduce donor loss from false-reactive tests, repeat-reactive donors without other evidence of infection were eligible to return. The aim was to evaluate the impact of anti-HBc testing on donor loss and to evaluate the effectiveness of this policy.
  
  
  METHODS
  For each donor in the first year of implementation (April 9, 2005-April 8, 2006) repeat-reactive for the presence of anti-HBc only but eligible to return (screening test for hepatitis B surface antigen-negative, plus not reactive to antibody to hepatitis B surface antigen [anti-HBs] and hepatitis B virus [HBV] DNA supplemental tests), 10 matched donors not reactive to the anti-HBc assay were selected. Return rates over 2 years were compared using conditional logistic regression. Testing outcomes were tabulated.
  
  
  RESULTS
  Over the first year of testing, 412,236 donors (951,423 donations) were tested for anti-HBc, and 4,489 donors were repeat-reactive (1.3% of first-time donors, 1.0% of repeat donors). Of these 85.6 percent were also reactive for the presence of anti-HBs and/or HBV DNA supplemental tests leaving less than 15 percent eligible to return, of whom 73 percent returned (vs. 90% of controls, p < 0.001). Of the 300 anti-HBc repeat-reactive returning donors, 74 percent were anti-HBc repeat-reactive again (thus permanently deferred), 19 percent were deferred for other reasons versus 14 percent of controls (p < 0.05), and 7 percent (21 donors) did not react and were eligible to continue donating.
  
  
  CONCLUSIONS
  Most donors repeat-reactive for the presence of anti-HBc likely have past exposure to HBV. If eligible, most are willing to return, but likely to test anti-HBc repeat-reactive again.
authors.affiliation: Department of Epidemiology, University of Ottawa, Ontario, Canada. sheila.o'brien@blood.ca
authors.forename: Sheila F
authors.initials: SF
authors.lastname: O'Brien
authors.forename: Qi-Long
authors.initials: QL
authors.lastname: Yi
authors.forename: Wenli
authors.initials: W
authors.lastname: Fan
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Fearon
authors.forename: Vito
authors.initials: V
authors.lastname: Scalia
authors.forename: Mindy
authors.initials: M
authors.lastname: Goldman
mesh_terms: D017677:Age Distribution; D001782:Blood Donors / Q000706:statistics & numerical data*; D002170:Canada; D016022:Case-Control Studies; D004279:DNA, Viral / Q000276:immunology; D046148:Donor Selection / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006509:Hepatitis B / Q000276:immunology*; D006510:Hepatitis B Antibodies / Q000276:immunology*; D006512:Hepatitis B Core Antigens / Q000276:immunology*; D006514:Hepatitis B Surface Antigens / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology; D006801:Humans; D016015:Logistic Models; D008297:Male; D011640:Public Policy; D012044:Regression Analysis
chemical_list: D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens