ACTA / VASGBI / BJA & RCoA Project Grant
The UK CAVIAR Study: The UK CArdiac and Vascular surgery after Intravenous iron Assessment of Response study
Dr Andrew Klein & Prof Toby Richards
Background
Anaemia before cardiac or vascular surgery is common, and is present in up to one third of patients. Anaemic patients are more likely to suffer complications during and after surgery, including death (twice as likely), prolonged hospital stay (an extra two days), and blood transfusion (risk more than doubled). The most common cause of anaemia before surgery is iron restriction, where a patient has enough iron in their body but can't use it properly. This is due to changes in their metabolism due to chronic disease or ill health. Theoretically, this can be treated with an infusion of intravenous iron, which can now be safely given in 15 minutes as an outpatient, and increases haemoglobin in around two or three weeks, meaning it could be given before surgery without delaying it. However, its use before major cardiac or vascular surgery hasn't been properly tested before.
Aims
To see if intravenous iron, when given to vascular and cardiac surgical patients who are anaemic before surgery, improves haemoglobin concentration and reduces the number of anaemic patients who go on to have surgery. Also, to define in which patients it is particularly effective so that we can target these patients in the future. Finally, to see how this affects patients' fitness before surgery and their outcome after surgery, including their time in intensive care and hospital and their quality of life.
Experimental design
Patients who are anaemic and can come to the pre-operative anaemia clinic will have the trial explained to them and offered the opportunity to take part. If they agree, various blood tests will be taken, and they will be given a 1g single dose of intravenous iron over 15 minutes in the clinic. The tests will then be repeated when they are admitted to hospital immediately before surgery. A number of patients will have their fitness assess before and after iron treatment, by assessing how far they can walk or how hard they can cycle on a fixed bicycle, using a carefully controlled and conducted test. Patients who are unable to attend the pre-operative anaemic clinic will also be asked if they mind having their blood tested so we can study them in comparison to those who were treated with iron. We cannot undertake a full size randomised controlled trial with the money available for this grant, so we have therefore devised what is called a cohort study, however, we do hope to do an even larger study in the future for which these results will be critical. Four UK centres will take part in this trial: Papworth (Cambridge) and Cardiff (Wales) for cardiac surgery; and Royal Free (London) and Bristol, for vascular surgery. We have calculated that, to see whether the increase in haemoglobin we expect to see is truly important, we will need to study 72 patients who receive intravenous iron, and another 72 patients who do not, in comparison.
