title: Mortality outcomes in patients transfused with fresher versus older red blood cells: a meta-analysis.
abstract: BACKGROUND
  Among transfused patients, the effect of the duration of red blood cell storage on mortality remains unclear. This study aims to compare the mortality of patients who were transfused with fresher versus older red blood cells.
  
  
  METHODS
  We performed an updated systematic search in the CENTRAL, MEDLINE, EMBASE and CINAHL databases, from January 2015 to October 2016. RCTs of hospitalized patients of any age comparing transfusion of fresher versus older red blood cells were eligible. We used a random-effects model to calculate pooled risk ratios (RRs) with corresponding 95% confidence interval (CI).
  
  
  RESULTS
  We identified 14 randomized trials that enrolled 26 374 participants. All-cause mortality occurred in 1219 of 9531 (12·8%) patients who received a transfusion of fresher red blood cells and 1810 of 16 843 (10·7%) in those who received older red blood cells (RR: 1·04, 95% CI: 0·98-1·12, P = 0·90, I2= 0%, high certainty for ruling out benefit of fresh blood, moderate certainty for ruling out harm of fresh blood). In six studies, in-hospital death occurred in 691 of 7479 (9·2%) patients receiving fresher red cells and 1291 of 14 757 (8·8%) receiving older red cells (RR: 1·06, 95% CI: 0·97-1·15, P = 0·81, I2= 0%, high certainty for ruling out benefit of fresh blood, moderate certainty for ruling out harm of fresh blood).
  
  
  CONCLUSIONS
  Transfusion of fresher red blood cells does not reduce overall or in-hospital mortality when compared with older red blood cells. Our results support the practice of transfusing patients with the oldest red blood cells available in the blood bank.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: C
authors.identifier: http://orcid.org/0000-0001-7209-9722
authors.initials: C
authors.lastname: Chai-Adisaksopha
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: P E
authors.initials: PE
authors.lastname: Alexander
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Guyatt
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.|Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Crowther
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.|Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.|McMaster Centre for Transfusion Research, McMaster University, Hamilton, ON, Canada.|Centre for Innovation Canadian Blood Services, Hamilton, ON, Canada.
authors.forename: N M
authors.initials: NM
authors.lastname: Heddle
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.|Population Health Research Institute, Hamilton, ON, Canada.
authors.forename: P J
authors.initials: PJ
authors.lastname: Devereaux
authors.affiliation: Meir Medical Centre Kfar Saba and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Ellis
authors.affiliation: SA Pathology Transfusion Service, Flinders Medical Centre and Flinders University, Adelaide, SA, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Roxby
authors.affiliation: Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: D I
authors.initials: DI
authors.lastname: Sessler
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.|Population Health Research Institute, Hamilton, ON, Canada.|Thrombosis & Atherosclerosis Research Institute, Hamilton, ON, Canada.
authors.forename: J W
authors.initials: JW
authors.lastname: Eikelboom
mesh_terms: D001793:Blood Preservation; D002423:Cause of Death; D016208:Databases, Factual; D017707:Erythrocyte Transfusion / Q000009:adverse effects; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D017052:Hospital Mortality; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D012306:Risk; D013997:Time Factors
keywords: blood processing; clinical trial; red cell component; transfusion therapy