The Age of BLood Evaluation (ABLE) randomised controlled trial: description of the UK-funded arm of the international trial, the UK cost–utility analysis and secondary analyses exploring factors associated with health-related quality of life and health-care costs during the 12-month follow-up
Authors: Walsh Timothy S , Stanworth Simon , Boyd Julia , Hope David , Hemmatapour Sue , Burrows Helen , Campbell Helen , Pizzo Elena , Swart Nicholas , Morris Stephen 
Published: October 2017

BackgroundAt present, red blood cells (RBCs) are stored for up to 42 days prior to transfusion. The relative effectiveness and safety of different RBC storage times prior to transfusion is uncertain.ObjectiveTo assess the clinical effectiveness and cost-effectiveness of transfusing fresher RBCs (stored for ≤ 7 days) compared with current standard-aged RBCs in critically ill patients requiring blood transfusions.DesignThe international Age of BLood Evaluation (ABLE) trial was a multicentre, randomised, blinded trial undertaken in Canada, the UK, the Netherlands and France. The UK trial was funded to contribute patients to the international trial and undertake a UK-specific health economic evaluation.SettingTwenty intensive care units (ICUs) in the UK, as part of 64 international centres.ParticipantsCritically ill patients aged ≥ 18 years (≥ 16 years in Scotland) expected to require mechanical ventilation for ≥ 48 hours and requiring a first RBC transfusion during the first 7 days in the ICU.InterventionsAll decisions to transfuse RBCs were made by clinicians. One patient group received exclusively fresh RBCs stored for ≤ 7 days whenever transfusion was required from randomisation until hospital discharge. The other group received standard-issue RBCs throughout their hospital stay.Main outcome measuresThe primary outcome was 90-day mortality. Secondary outcomes included development of organ dysfunction, new thrombosis, infections and transfusion reactions. The primary economic evaluation was a cost–utility analysis.ResultsThe international trial took place between March 2009 and October 2014 (UK recruitment took place between January 2012 and October 2014). In total, 1211 patients were assigned to receive fresh blood and 1219 patients to receive standard-aged blood. RBCs were stored for a mean of 6.1 days [standard deviation (SD) ± 4.9 days] in the group allocated to receive fresh blood and 22.0 days (SD ± 8.4 days) in the group allocated to receive standard-aged blood. Patients received a mean of 4.3 RBC units (SD ± 5.2 RBC units) and 4.3 RBC units (SD ± 5.5 RBC units) in the groups receiving fresh blood and standard-aged blood, respectively. At 90 days, 37.0% of patients in the group allocated to receive fresh blood and 35.3% of patients in the group allocated to receive standard-aged blood had died {absolute risk difference 1.7% [95% confidence interval (CI) –2.1% to 5.5%]}. There were no between-group differences in any secondary outcomes. The UK cohort comprised 359 patients randomised and followed up for 12 months for the cost–utility analysis. UK patients had similar characteristics and outcomes to the international cohort. Mean total costs per patient were £32,346 (95% CI £29,306 to £35,385) in the group allocated to receive fresh blood and £33,353 (95% CI £29,729 to £36,978) in the group allocated to receive standard-aged blood. Approximately 85% of the total costs were incurred during the index hospital admission. There were no significant cost differences between the two groups [mean incremental costs for those receiving fresh vs. standard-aged blood: –£231 (95% CI –£4876 to £4415)], nor were there significant differences in outcomes (mean difference in quality-adjusted life-years –0.010, 95% CI –0.078 to 0.057).LimitationsAdverse effects from the exclusive use of older RBCs compared with standard or fresh RBCs cannot be excluded.ConclusionsThe use of RBCs aged ≤ 7 days confers no clinical or economic benefit in critically ill patients compared with standard-aged RBCs.Future workFuture studies should address the safety of RBCs near the end of the current permitted storage age.Trial registrationCurrent Controlled Trials ISRCTN44878718.FundingThis project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 21, No. 62. See the NIHR Journals Library website for further project information. The international ABLE trial was also supported by peer-reviewed grants from the Canadian Institutes of Health Research (177453), Fonds de Recherche du Québec - Santé (24460), the French Ministry of Health Programme Hospitalier de Recherche Clinique (12.07, 2011) and by funding from Établissement Français du Sang and Sanquin Blood Supply.