False positive viral marker results in blood donors and their unintended consequences

Abstract

False positive (FP) viral marker results in blood donors continue to pose many challenges. Informing donors of FP results and subsequent deferral can result in stress and anxiety for donors and additional complexity and workload for blood services. Donor management strategies need to balance the requirement to minimise donor anxiety and inconvenience while maintaining sufficiency of supply. Decisions about how and when to inform donors of FP results and determine deferral periods can be difficult as FP results, while often transitory, can take up to several years to resolve. Additional complexities include the interpretation of indeterminate serological confirmatory testing without detectable viral RNA or non-discriminated NAT results with concomitant anti-HBc reactivity - both may be due to FP results, but the former may also represent past infection and the later may represent occult hepatitis B infection. In this review we discuss strategies to minimise indeterminate serological confirmatory results, possible donor deferral policies and the impact on donors when notified of FP results. We also provide some new data from Australia that address the challenge of interpreting non-discriminated NAT results with concomitant anti-HBc reactivity. Ultimately, the challenge is for each blood service to develop appropriate strategies for donor management, taking into account local information and requirements.

Keywords: NAT non-discriminated reactive; blood donor testing; false positive; indeterminate.