Blood donation screening for hepatitis B virus markers in the era of nucleic acid testing: are all tests of value?

BACKGROUND

The American Red Cross implemented hepatitis B virus (HBV) minipool (MP)-nucleic acid testing (NAT) in June 2009, in addition to existing tests for hepatitis B surface antigen (HBsAg) and antibodies to hepatitis B core antigen (anti-HBc). The value of all three tests was evaluated.

STUDY DESIGN AND METHODS

HBsAg, anti-HBc, and HBV DNA (Ultrio MP-NAT, Gen-Probe/Novartis) donation results were analyzed during a 12-month period (July 1, 2009-June 30, 2010). Additional testing by individual-donation (ID) polymerase chain reaction (PCR) to confirm donor infection was performed when any HBV screening test was reactive or positive, except in the case of HBsAg neutralization-positive, anti-HBc-reactive samples. Numbers of blood donations identified as reactive or positive versus nonreactive or negative were compared.

RESULTS

Of about 6.5 million donations, 699 were defined as from HBV-infected donors, of which 64% (444) were reactive for all three markers. More than 99% (697) had reactivity to one or both serologic tests with 68% (477) showing reactivity by MP-NAT. Only two donations were DNA-positive, seronegative NAT-yield donations (1 per 3.23 million), fewer than expected (p = 0.0075). Among MP-NAT-reactive donors, only small numbers represented early infection (2 or 0.4% with negative serology and 10 or 2.1% who were HBsAg confirmed positive, anti-HBc nonreactive). Of the 142 occult HBV-infected donors, 85% were MP-NAT nonreactive requiring ID-PCR for detection (121 or 54.5% of all MP-NAT nonreactives vs. 21 or 4.4% of all MP-NAT reactives).

CONCLUSIONS

The HBV DNA-positive yield rate from MP-NAT was lower than expected, likely representing the rarity of such findings even in very large studies. With the implementation of HBV MP-NAT, the value of maintaining anti-HBc for the detection of low-level HBV DNA-positive donors was confirmed; however, HBsAg screening showed no blood safety value.