title: Comparison of Two Test Strategies for Clarification of Reactive Results for Anti-HBc in Blood Donors.
abstract: OBJECTIVE
  Testing for antibodies against hepatitis B core antigen (anti-HBc) was introduced to detect blood donors suffering from occult hepatitis B infection. Confirmation of specification of reactive results in the anti-HBc screening assay is still a challenge for blood donation services.
  
  
  METHODS
  Two different test strategies for confirmation of specification of reactive anti-HBc tests, one performed in our institute and one suggested by the German authority (Paul-Ehrlich-Institut (PEI)), were compared. The first strategy is based on one supplemental anti-HBc test, the other requires two supplemental anti-HBc tests.
  
  
  RESULTS
  389 samples from 242 donors were considered. Both test strategies yielded concordant results in 117 reactive samples termed 'true-positive' or 'specificity confirmed', in 156 reactive samples termed 'false-positive' or 'specificity not confirmed', and in 99 negative samples. In 17 samples obtained from 11 donors, both test strategies gave discrepant results ('false-positive' but 'specificity confirmed'). In 10 of 11 donors, a real HBV infection was very unlikely, one remained unclear. 30 donors considered 'false-positive' became negative in all anti-HBc tests after follow-up testing and thus eligible for donor re-entry.
  
  
  CONCLUSIONS
  The test strategy suggested by the PEI yielded no additional information but induced an overestimation of HBV infections and unnecessary look-back procedures. Many anti-HBc-reactive donors can be regained after follow-up testing.
authors.affiliation: Institute of Transfusion Medicine, University Hospital of Schleswig-Holstein, Lübeck, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Juhl
authors.affiliation: Institute of Medical Microbiology and Hygiene, University Hospital of Schleswig-Holstein, Lübeck, Germany.
authors.forename: Johannes K-M
authors.initials: JK
authors.lastname: Knobloch
authors.affiliation: Institute of Transfusion Medicine, University Hospital of Schleswig-Holstein, Lübeck, Germany.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Görg
authors.affiliation: Institute of Transfusion Medicine, University Hospital of Schleswig-Holstein, Lübeck, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Hennig
keywords: Anti-HBc; Blood donor; Donor re-entry; HBV DNA; Hepatitis B virus