Anti-HBc screening of blood donors:: a comparison of nine anti-HBc tests

Backgrounds and Objectives Since voluntary introduction of hepatitis B virus (HBV) minipool nucleic acid amplification technology (NAT) at the German Red Cross, the expected residual risk of a transfusion-associated HBV infection has been estimated to be 1 : 500 000 - about 10 times higher than for human immunodeficiency virus (HIV) or hepatitis C virus (HCV) infection. Donors demonstrating chronic positivity for antibody to hepatitis B core antigen (anti-HBc), negativity for hepatitis B surface antigen (HBsAg) and polymerase chain reaction (PCR)-negative with a low virus load are a major cause of this increased risk. Materials and Methods Ten-thousand blood donors from our blood-donation centre were screened for anti-HBc using the current PRISM (R) HBc and the new PRISM (R) HBcore assay to evaluate the diagnostic sensitivity and specificity of these tests. PRISM (R) HBc- or PRISM (R) HBcore-reactive samples were further analysed using seven additional tests for anti-HBc, two tests for antibody to hepatitis B surface antigen (anti-HBs), one test for antibody to hepatitis B envelope antigen (anti-HBe) and three HBV NAT assays. Results From a total of 10 000 donors, nine and 14 samples were reactive only in the PRISM (R) HBc and the PRISM (R) HBcore, respectively, whereas 165 samples were reactive in both anti-HBc assays. Further analysis of these 188 anti-HBc-reactive specimens in a total of nine different anti-HBc assays revealed concordant results for 162 (86.2%) specimens. Sample cut-off values for anti-HBc were significantly (P < 0.01) lower for anti-HBc-only reactive samples compared with specimens that were also reactive for anti-HBs or anti-HBe. Conclusions Both PRISM anti-HBc assays revealed that approximate to 1.8% of non-prescreened blood donors from Germany were reactive for anti-HBc. Although sensitivity was comparable between both assays, specificity was increased significantly with the PRISM (R) HBcore. High anti-HBc sample cut-off values were indicative for reactivity in other HBV parameters and for concordant results in the nine different anti-HBc assays. Look-back investigations are necessary to estimate the infection risk both of anti-HBc-only positive and of anti-HBc/anti-HBs-positive blood transfusions.