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A multi-centre randomised controlled trial of Transfusion Indication Threshold Reduction on transfusion rates, morbidity and healthcare resource use following cardiac surgery

Dates: 2009-2014
Funding: NIHR Health Technology Assessment Programme
Collaborators: University of Bristol, University of Leicester
Information: Sarah Wordsworth, Liz Stokes

Indications for blood transfusion after cardiac surgery are poorly defined. Unnecessary blood transfusions increase healthcare costs both directly, as blood is scarce and expensive, and indirectly, due to complications associated with transfusion. Most decisions to transfuse after surgery are made on a patient's haemoglobin (Hb) level. The level causing doctors to transfuse varies widely and randomised trials in non-cardiac surgical fields have shown that lowering the level that 'triggers' transfusion reduces complications and blood use. This multicentre trial was carried out at 17 UK hospitals. Patients whose Hb level dropped below the level at which transfusion is conventionally given were randomised to have decisions made: (a) as standard care ('liberal'), or (b) only when the Hb level dropped to a lower, 'restrictive' level. The trial's primary outcome was a serious infection (sepsis or wound infection) or an ischaemic event (stroke, heart attack or kidney failure) during the first 3 months after surgery. The health economic evaluation was designed as an integral component of the trial and captured detailed information on patient-level resource use and health outcomes to facilitate an estimation of the cost-effectiveness of using a 'restrictive' transfusion threshold compared to a 'liberal' transfusion threshold.


Findings: There was no significant difference in the primary outcome, which was observed in 35.1% of patients in the 'restrictive' group and 33.0% of patients in the 'liberal' group. There were more deaths however in the 'restrictive' group than the 'liberal' group (4.2% versus 2.6%). There was a clear difference in the costs of red cell transfusions between the groups: average costs were £287 in the 'restrictive' group and £427 in the 'liberal' group. When all health care costs up to 3 months after surgery were considered however, costs were similar in the two groups (on average, £10,636 in the 'restrictive' group and £10,814 in the 'liberal' group if the cost of the index surgical procedure was excluded, and £17,945 in the 'restrictive' group and £18,127 in the 'liberal' group if the cost of the index surgical procedure was included). Results of the cost-effectiveness analyses will be published in the forthcoming HTA report in 2015.


Patients having heart surgery do not benefit if doctors wait until they become substantially anaemic before giving a transfusion.

Publications

Murphy, GJ, Pike, K, Rogers, CA, Wordsworth, S, Stokes, EA, Angelini, GD, and Reeves, BC (2015). Liberal or Restrictive Transfusion after Cardiac Surgery. N Engl J Med, 372(11):997-1008.

Brierley RC. et al, (2014). A multi-centre randomised controlled trial of Transfusion Indication Threshold Reduction on transfusion rates, morbidity and healthcare resource use following cardiac surgery: study protocol. Transfus Apher Sci, 50, 451 - 461