The mantra of blood safety: Time for a new tune?

Abstract

Over the past years, a paradigm of blood safety in established blood delivery systems has evolved which proposes the concept of the 'Safety Tripod'. In this paradigm, blood safety is approached through a combination of appropriate donor selection, screening tests for pathogens and pathogen reduction. All three 'legs' of the tripod are considered as equally essential contributors to the final safety of transfused blood, blood components and plasma derivatives. Regulatory measures and applicable standards have also emphasized all three components. With the increasing burden of 'zero risk' in public and political perception, it is difficult to question the immutability of this paradigm. However, its relevance and appropriateness is increasingly open to critical assessment. As the number of putative risks from blood-borne infections continues to mount, selecting donors with minimal geographical and behavioural risks is increasingly problematic and may lead to the introduction of known risks into the donor pool in efforts to minimize unknown ones. While nucleic acid technology has resulted in the ability to develop screening tests in a more rapid fashion than standard serology, the complexity and expense of screening platforms affects the logistics of blood delivery and raises the spectre of an unending series of tests to screen out each potential blood-borne pathogen. The potential for pathogen inactivation as the main route of assuring blood safety has been demonstrated for plasma derivatives, where the current excellent safety level has been achieved through inactivation techniques irrespective of the other legs of the tripod. The advent of such technology for the fresh components of mainstream blood banking therefore offers a promising approach to assuring safety in the absence of increasingly difficult and impractical selection and screening procedures. However, it is difficult to envisage these technologies in the current blood centre setting, and their incorporation can only be effected if the blood banking sector progresses further down the road to the manufacturing, rather than medical laboratory, environment. Furthermore, blood transfusion therapy needs to reflect other advances in therapeutic practice, and continuing evidence that much of blood component usage has no evidence base and is inappropriate must start feeding into blood safety policy if the benefits of technology are to be harvested. Measures for appropriate usage need to incorporate the significant advances in bloodless medicine which have been reported over the past decade. The rapid development of blood substitutes, particularly recombinant proteins, needs to be embraced and furthered by the transfusion community. All these factors can contribute to assuring the safety of blood products by channelling resources into measures for products which cannot be substituted in the near future. The transfusion community needs to embrace these developments and contribute a leadership role to their progression, rather than the suspicion with which it currently greets most of them. Thus, rather than a tripod, the future basis for blood safety should rather rest on the sophisticated application of a range of measures, an acceptance that some traditional measures may have to assume a secondary role, and the ever present need for communicating in a transparent and accountable way the relevant risks and preventive measures to a (justifiably) sceptical public and political framework.