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: