Update on the status of pathogen inactivation methods

Abstract

Background Improvements in donor selection criteria and donor testing have reduced the risks of transfusion‐transmitted diseases to remarkably low levels in developed countries. Residual risk remains because of window period donations and the potential for error. Developing countries may not have implemented all these safety measures fully, however. In all countries, tests with limited sensitivity (e.g. for detection of bacterial contamination) and ‘emerging’ pathogens, for which accurate tests have not been developed, pose continued threats to recipients.Results Pathogen inactivation (PI) has brought a welcome level of safety to plasma derivatives, and an increasing number of techniques are available for labile blood components. The toxicity profile of these techniques appears acceptable. Although the processes inevitably cause a reduction in the content or efficacy of the component, transfusions of the inactivated components appear to provide clinically useful outcomes. Transfusion of pathogen‐inactivated plasma components is in widest use across multiple countries, and an increasing number of centres in multiple countries are adopting PI of platelet units as well. Development of techniques applicable to red cell units continues and preliminary success has been claimed. Not all reports of clinical use of PI platelets and plasma have been positive, however. Differences in bleeding rates may be attributable to different approaches to patient evaluation. Some regulatory agencies continue to place emphasis on the potential for pulmonary complications, although reanalysis of previous data indicates no increased risk of pulmonary toxicity. Multiple cost‐effectiveness analyses have demonstrated that currently available PI techniques will likely reduce the residual risk of known pathogens by only a small amount and thus have marginal cost‐effectiveness ratios in the range of $500 000–1 500 000/QALY (this is worse than for most commonly accepted medical procedures but not out‐of‐line in comparison to other blood safety interventions). The presumed effectiveness of current bacterial detection approaches is central to these analyses as bacteria remain the most frequently transmitted pathogen with culture detecting only 30–50% of contaminated units. An analysis of residual risk indicates that while techniques applicable across all components will be necessary to achieve the desired maximal effect of PI, implementing PI for plasma and platelets with currently available technology would reduce transmissions of both acute and chronic emerging disease agents by 40%.Conclusions The decision whether to implement PI is a complex one with ethical, societal and financial aspects. The ability to improve the safety of transfusion for recipients, particularly with respect to bacteria and emerging threats, is an important augmentation to our commitment to patients.