Pathogen-reduced platelets for the prevention of bleeding.

Abstract

Blood for transfusion is collected from donors and then processed and stored as bags of different blood components. One of these components is platelets. Platelets are cells which help the body form clots and prevent bleeding. As for all transfusions, there are risks related to giving platelets to patients, including a small risk of transfusion-transmitted infections. A number of methods are used to minimise the risk of transfusion-transmitted infections, including careful selection of donors and rigorous donor testing. One new method of preventing infection is pathogen reduction by which, through a process of adding chemicals to the donated platelets and exposing them to a wavelength of ultraviolet light, the number of infecting organisms can be reduced. The aim of this review was to assess whether these specially treated, pathogen-reduced platelets, work as effectively as normal platelets when transfused. Specifically, can they stop or prevent bleeding as well as standard platelets, do they produce the same increase in platelet count and does their use affect further transfusion requirements? Also, this review assessed whether pathogen-reduced platelets are as safe as normal platelets - for example, are they associated with any difference in the rate of death following transfusion and are there any side effects associated with the use of these products? Ten randomised controlled trials, involving 1422 patients, were included assessing two different pathogen-reduced platelet transfusion products, Intercept® and Mirasol® platelets, as compared with standard platelets. Nine trials assessed Intercept® platelets and one trial Mirasol® platelets. The 10 trials had different designs with varying methods of outcome assessment and durations of follow-up. Bleeding was assessed as 'any bleeding', 'clinically significant' and 'severe' at short (up to 48 hours) or long (more than seven days) follow-up periods. There was no difference in 'clinically significant' or 'severe bleeding', mortality, transfusion reactions or adverse events between pathogen-reduced and standard platelets. However, there were significantly poorer responses following the transfusion of pathogen-reduced platelets with a requirement for more platelet transfusions. Due to the limitations of the trial sizes and their designs, there is not enough evidence available to be sure that pathogen-reduced platelets work as effectively as standard platelets to prevent bleeding.