ABLE

ABLE: Age of Transfused Blood in Critically Ill Adults

Lacroix et al. Canadian Critical Care Trials Group. NEJM 2015; 372:1410-1418. doi:10.1056/NEJMoa1500704

Clinical Question

  • In critically ill patients requiring blood, does transfusion with “fresh” RBC’s (stored for 8 days or less) compared with standard issue RBCs (stored 2-42 days) reduce 90 day mortality?

Design

  • Multicenter, randomised controlled trial
  • Randomisation occurred by a centralised computer with stratification according to study site
  • Patients were assigned in a 1:1 ratio to one of the two study groups with the use of permuted blocks of varying sizes of 6, 8 or 10
  • Intention to treat analysis
  • Interim analyses occurred after each consecutive group of 500 patients had been followed for 90 days
  • Estimated that 2266 patients was required for the study to be 90% powered to detect an absolute difference in mortality of 5% from a baseline mortality of 25%

Setting

  • 64 tertiary care intensive care units in Canada and Europe
    • 26 Canada, 20 UK, 10 France, 7 Netherlands, 1 Belgium
  • March 2009 – May 2014

Population

  • Inclusion:
    • Patients administered RBC transfusion up to seven days post ICU-admission
    • Anticipated length of mechanical ventilation of at least 48 hours
  • Exclusion: < 18 years; RBC transfusion prior to ICU admission; terminal illness with life expectancy < 3 months; undergone elective cardiac surgical care during the same hospitalisation; futility; refusal to receive transfusion; intensivist refused participation in study; no available RBCs in the blood bank with a storage time of 7 days or less; requirement of more than one unit of uncross-matched blood; patients requiring specifically matched blood due to autoantibodies
  • 2510 patients randomised of whom outcome data available for 2430
    • baseline characteristics were similar in both groups
    • mean APACHE 21.8
    • mean length of ICU stay 2.4 days
    • mostly medical (71%) and emergency patients (96.7%)
    • most required invasive ventilation (97.4%) and vasoactive support (62.8%)
    • mean pretransfusion Hb was 7.7g/dl

Intervention

  • ‘Fresh’ blood transfusion – stored for 8 days or less
    • 1211 patients
    • protocol specified that if red cells < 8 days old were not available then the freshest compatible red cells were issued. The average duration of storage was 6.1 +/- 4.9 days
      • 84% received only RBCs stored for <8 days

Control

  • Standard blood transfusion – stored 2 – 42 days
    • 1219 patients
    • the oldest compatible red cells were issued. The average duration of storage was 22.0 +/- 8.4 days

For both intervention and control groups:

  • All blood was leukoreduced before storage and suspended in saline-adenine-glucose-mannitol (SAGM)
  • Local guidelines and practice for bedside transfusion were adopted
  • All decisions regarding patient care was at the discretion of the attending physicians and the clinical team

Outcome

  • Primary outcome: 90 day mortality
    • 448 patients (37%) vs. 430 patients (35%) (Absolute Risk Difference 1.7%; 95% CI -2.1-5.5)
  • Secondary outcomes: No statistical difference between the groups in any of the outcomes
    • time to death in ICU, in hospital and by day 28
    • major illness including MODS, ARDS, heart failure, cardiac ischaemia or MI, DVT or PE
    • duration of respiratory support
    • duration of haemodynamic suppport
    • duration of renal support
    • length of stay in the hospital
    • transfusion reactions
  • Subgroup analysis: No difference
    • 90d mortality in the patients who received a transfusion (excluded 94 patients who did not actually receive blood
    • 90d mortality in the patients who only received blood that had been stored for < 8 days vs those that had received blood stored for more than 7 days

Authors’ Conclusions

  • Transfusion of fresh red cells, as compared with standard-issue red cells, did not decrease the 90-day mortality among critically ill patients

Strengths

  • Concealment of the age of the red cells by an opaque sticker affixed over the expiration and collection dates
  • Blood transfusion technologists refrained from releasing information on storage duration to all clinical and research personnel
  • Protocol, including details of trial conduct and the statistical analysis plan was published a priori
  • Only 3.9% of patients lost to follow up. This was less than the number anticipated when the study was planned
  • The rate of adherence to the transfusion protocol was 95.4%

Weaknesses

  • 94 patients (3.9%) did not receive any blood transfusion. This has been considered in the sub-group analysis
  • Lack of uniform guideline or protocol across centres for transfusion. However, a pragmatic study and this is acknowledged in the manuscript

The Bottom Line

  • This study shows that fresh blood which has been stored for < 8 days is no better than blood stored up to 42 days. Transfusion triggers and processes for safe administration of blood are probably more important

External Links

Metadata

Summary author: @stevemathieu75
Summary date: 15th July 2015
Peer-review editor: @davidslessor

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