title: Red blood cell processing methods and in-hospital mortality: a transfusion registry cohort study.
abstract: BACKGROUND
  Quality of red blood cells (RBCs) varies depending on the method of processing the whole blood donation, and the method of processing might affect outcomes in patients transfused RBCs. We aimed to establish whether an association exists between in-hospital mortality and RBC processing method and duration of storage.
  
  
  METHODS
  We did a retrospective registry cohort study using data from three acute care hospitals in Hamilton, ON, Canada, and Canadian Blood Services over a 6-year period (2008-14). Adult patients (≥18 years) who were admitted to hospital and who received RBC transfusions were included in the study. All transfused RBCs were characterised by the method of processing (red cell filtered or whole blood filtered) and storage age (fresh 1-7 days, mid 8-35 days, and old 36-42 days). The primary outcome was in-hospital mortality. We used Cox proportional hazards regression with time-dependent stratification variables and fixed stratification variables, and controlled for patient covariates.
  
  
  RESULTS
  Between April 1, 2008, and March 31, 2014, 91 065 RBC transfusions were given to 23 634 adults who were included in the analyses. When storage duration was included in the model, in-hospital mortality was significantly increased with fresh whole blood filtered units compared with the reference group of mid-age red cell filtered units (hazard ratio 2·19, 95% CI 1·09-4·42; p=0·033). Differences between other age and processing categories were not significant.
  
  
  CONCLUSIONS
  The potential effect of whole blood processing methods on patient outcomes is worthy of further investigation, since adverse outcomes could be reduced by minor changes to blood processing methods and inventory management policies.
  
  
  BACKGROUND
  Canadian Blood Services, Health Canada, and the Canadian Institutes of Health Research.
authors.affiliation: Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON Canada; Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada. Electronic address: heddlen@mcmaster.ca.
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Heddle
authors.affiliation: Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON Canada; Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Arnold
authors.affiliation: Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada; Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Acker
authors.affiliation: Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON Canada.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON Canada.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Barty
authors.affiliation: Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON Canada.
authors.forename: John W
authors.initials: JW
authors.lastname: Eikelboom
authors.affiliation: Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON Canada; Utilization Medical Services and Innovation, Canadian Blood Services, Ancaster, ON, Canada.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Webert
authors.affiliation: London Health Sciences Centre, Victoria Hospital, London, ON, Canada.
authors.forename: Cyrus C
authors.initials: CC
authors.lastname: Hsia
authors.affiliation: Epidemiology and Surveillance, Canadian Blood Services, Ottawa, ON, Canada.
authors.forename: Sheila F
authors.initials: SF
authors.lastname: O'Brien
authors.affiliation: Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, ON, Canada.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cook
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001790:Blood Physiological Phenomena; D002170:Canada; D004355:Drug Stability; D004356:Drug Storage / Q000379:methods*; D017707:Erythrocyte Transfusion / Q000379:methods* / Q000401:mortality*; D004912:Erythrocytes / Q000502:physiology; D005260:Female; D005374:Filtration / Q000379:methods*; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D012042:Registries; D012189:Retrospective Studies; D012306:Risk; D013997:Time Factors