Review

Ahead-of-Print

The Red Blood Cell-Improving Transfusions for Chronically Transfused Recipients (RBC-IMPACT) study: protocol description of an international multi-site observational clinical study

Authors

Key words: red blood cells, sickle cell disease, thalassemia, chronic transfusion, hemoglobin increment
Publication Date: 2025-05-09

Abstract

Background - Variability in blood donors, components, and recipients are known to affect transfusion outcomes, yet the combined effects of these factors remains unclear.

Materials and methods - The Red Blood Cell - Improving Transfusions for Chronically Transfused Recipients (RBC-IMPACT) study was a multi-center longitudinal study conducted in the United States (US) and Brazil over two years to investigate RBC survival after transfusion (Aim 1) and acute increase in iron post transfusion (Aim 2) (see https://clinicaltrials.gov/study/NCT05255445). The US RBC-IMPACT study included patients with thalassemia and sickle cell disease (SCD) and, in Aim 2 only, children with hematology-oncology diseases with a hypoproliferative bone marrow. In Brazil, the study was conducted within an established SCD cohort. Blood samples were collected immediately before and after RBC transfusion to measure hemoglobin (Hb), hemoglobin A (HbA) in SCD, and markers of iron and hemolysis. Samples were collected two hours post transfusion in a subset of participants receiving primarily single unit transfusions for Aim 2. Transfusate samples were collected from transfused units. Single nucleotide polymorphism array typing of donors and recipients to measure genetic variants including those associated with increased in vitro hemolysis of stored RBCs was conducted. Comprehensive information regarding donors, components and some recipient data were linked to key clinical data extracted from recipients’ medical records to assess factors associated with RBC transfusion effectiveness.

Results - The outcomes for Aim 1 were RBC survival between successive transfusions, calculated as ΔHbA per day for SCD and by ΔHb per day for thalassemia, and Δbilirubin for both patient groups. The primary outcome for Aim 2 was change in serum iron from before to 2 hours after transfusion.

Discussion - This study will be the most detailed and granular evaluation of the predictive variables that may optimize RBC effectiveness and safety in these chronically transfused patient populations.

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Authors

Matthew S. Karafin - Department of Pathology and Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, NC, USA https://orcid.org/0000-0001-7533-6842

Shannon Kelly - Department of Pediatrics, University of California, San Francisco Benioff Children’s Hospital Oakland, Oakland, CA, USA

Kathleen M. Chapman - Westat, Rockville, MD, USA https://orcid.org/0009-0007-0837-9018

Lisa Baumann Kreuziger - Versiti Blood Research Institute, Versiti, Milwaukee, WI, USA https://orcid.org/0000-0002-1171-0548

John P. Manis - Department of Pathology, Harvard Medical School and Boston Children's Hospital, Boston, MA, USA

Carla Dinardo - Division of Immunohematology, Faculdade de Medicina da Universidade de Sao Paulo and Fundacao Pro Sangue, São Paulo, Brazil

Cassandra D. Josephson - Departments of Oncology, Pediatrics, Pathology, Johns Hopkins University School of Medicine and Johns Hopkins All Children’s Hospital, Baltimore, MD, and St. Petersburg, FL, USA https://orcid.org/0000-0003-2543-991X

Mars Stone - Vitalant Research Institute, San Francisco, CA, USA and Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA https://orcid.org/0000-0001-5619-2767

Nareg H. Roubinian - Vitalant Research Institute, San Francisco, CA, USA; Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA; Kaiser Permanente Division of Research, Pleasanton, CA, USA https://orcid.org/0000-0002-1063-6155

Brian Branchford - Versiti Blood Research Institute, Versiti, Milwaukee, WI, USA https://orcid.org/0000-0002-4076-270X

Bruce S. Sachais - New York Blood Center Enterprises, New York, NY, USA

Benyam Hailu - National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA

Ester C. Sabino - University of Sao Paulo, Sao Paulo, Brazil https://orcid.org/0000-0003-2623-5126

Eldad A. Hod - Department of Pathology & Cell Biology, Columbia University Irving Medical Center, New York, New York, USA https://orcid.org/0000-0002-2367-9509

Brian Custer - Vitalant Research Institute, San Francisco, CA, USA; Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA https://orcid.org/0000-0001-6251-366X

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