Centre-based comparison of double versus single prevention strategy on transfusion-transmitted cytomegalovirus in at-risk haemopoietic stem cell transplant patients and a state survey on cytomegalovirus-seronegative ordering practises.

Background: Universal leucocyte depletion reduces the risk of transfusion-transmitted cytomegalovirus; however, many clinicians still prescribe cytomegalovirus seronegative units.

Aim: Our retrospective study aims to confirm the low risk of transfusion-transmitted cytomegalovirus with leucocyte depletion alone and demonstrate the ongoing variability in cytomegalovirus seronegative transfusion prescribing.

Methods: Over a 9-year period (July 2009-July 2018), occurrences of transfusion transmitted cytomegalovirus in cytomegalovirus seronegative donor/recipient haemopoietic stem cell transplant pairs were compared at one allogeneic haemopoietic stem cell transplant centre providing cytomegalovirus seronegative blood products and leucocyte depletion (double prevention) versus another providing leucocyte depletion only (single prevention). Retrospective chart audit identified patient demographics, blood product exposure and cytomegalovirus infection by polymerase chain reaction. A separate audit examined cytomegalovirus seronegative blood product ordering in a broader range of hospital types.

Results: We identified 122 and 66 cytomegalovirus-negative donor/recipient haemopoietic stem cell transplant pairs using double and single transfusion prevention strategy respectively. Transfusion exposure to red cells and pooled platelets was similar, although more apheresis platelets were used in the double prevention group. The cytomegalovirus infection rate was 3 (2.4%) and zero in the double and single prevention groups respectively. Cytomegalovirus seronegative unit ordering was not limited to hospitals with obstetric or neonatal populations, suggesting ongoing reliance of cytomegalovirus seronegative units outside this population.

Conclusions: The analysis suggests a double prevention strategy does not provide additional protection against transfusion-transmitted cytomegalovirus. There is ongoing variability in the acceptance of leucocyte depletion alone despite the low risk of cytomegalovirus infection.