Transfusion of prion-filtered red cells does not increase the rate of alloimmunization or transfusion reactions in patients: results of the UK trial of prion-filtered versus standard red cells in surgical patients (PRISM A).

This study, conducted for the UK Blood Transfusion Services ( UKBTS), evaluated the clinical safety of red cells filtered through a CE-marked prion removal filter (P-Capt™). Patients requiring blood transfusion for elective procedures in nine UK hospitals were entered into a non-randomized open trial to assess development of red cell antibodies to standard red cell ( RCC) or prion-filtered red cell concentrates ( PF- RCC) at eight weeks and six months post-transfusion. Patients who received at least 1 unit of PF- RCC were compared with a control cohort given RCC only. About 917 PF- RCC and 1336 RCC units were transfused into 299 and 291 patients respectively. Twenty-six new red cell antibodies were detected post-transfusion in 10 patients in each arm, an overall alloimmunization rate of 4·4%. Neither the treatment arm [odds ratio ( OR) 0·93, 95% confidence interval ( CI) 0·3, 2·5] nor number of units transfused ( OR 0·95, 95% CI 0·8, 1·1) had a significant effect on the proportion of patients who developed new alloantibodies. No pan-reactive antibodies or antibodies specifically against PF- RCC were detected. There was no difference in transfusion reactions between arms, and no novel transfusion-related adverse events clearly attributable to PF- RCC were seen. These data suggest that prion filtration of red cells does not reduce overall transfusion safety. This finding requires confirmation in large populations of transfused patients. [ABSTRACT FROM AUTHOR]