The Impact of Red Cell Age on Product Utilization in the Chronically Transfused Outpatient Population (ABC-TOP)

Background: Chronically transfused medical outpatients comprise a significant proportion of transfusion recipients annually. At this time, the impact of red cell transfusion on patient outcomes in this patient population is unknown.

Objective: Our goal is to prospectively evaluate impact of red cell age on product utilization in a cohort of chronically transfused medical outpatients randomized to receive red blood cells that are fresh (≤ 7 days from collection) or aged (>21-42 days from collection). To our knowledge, no other studies with a similar design or objective have been published.

Patient population and study design: Patients meeting eligibility criteria will be invited to participate in our study. Our chronically transfused outpatient population is defined as adults who are receiving 2 or more red cell units per month for at least 3 consecutive months in an ambulatory clinic setting within the Calgary Zone.

We plan to incorporate both prospective and retrospective data collection and analysis in our study design. All eligible, consenting participants will be randomized into one of the two study arms. Investigators and participants will be blinded to participant group assignment.

Laboratory parameters and red cell transfusion: Parameters of usual pre-transfusion bloodwork will be followed, including complete blood count (CBC) and ferritin levels. Red cell transfusion volumes for chronic transfusion throughout the study will be determined according to a locally established protocol to achieve a post-transfusion hemoglobin (Hb) of 95-105 g/dL. Given that 1 adult unit of red cells raises the baseline Hb by approximately 10 g/L, the following volumes will be given to patients during a single visit based on their pre-transfusion CBC: Hb <75 = 3 units, Hb 75-84 = 2 units, Hb 85-94 = 1 unit, Hb ≥95 = no transfusion. A routine post-transfusion CBC will not be performed. According to usual care, participants will have a standing order to perform a CBC at least weekly, or if they have subjective symptoms of anemia to help guide subsequent transfusions.

Study participants will receive blood transfusion in usual locations designated within the Calgary Zone for administration of chronic blood transfusions. These include medical daycare units at the Foothills Medical Center, Tom Baker Cancer Center, Peter Lougheed Center, and South Health Campus. Nurses will administer blood transfusions according to standard practice, without change in transfusion protocol despite patient study participation.

Duration of participation will be 1 year from the time of enrollment. Participant health record access will be required for collection of demographic information and retrospective data involving any transfusions received within 1 year prior to enrollment to establish transfusion chronicity and health patterns. Outcomes will be based on a comparison of results between the study groups. Prospectively collected data based on red cell age will additionally be compared to retrospective transfusion related information (including red cell transfusion frequency and blood age) from within 1 year from the time of enrollment, if available. We plan to enroll a maximum total of 60 participants, with assignment of 30 patients into each group.