Why experts are rethinking blood transfusions

From ABC Health and Wellbeing, 4 August 2015:

Countless lives have been saved in the hundreds of years that people have been receiving blood transfusions.

Transfusions replenish blood lost through trauma, illness or surgery. They are a medical safety net; there for when surgery doesn’t quite go according to plan, and patients need a little top-up. They are also a lifeline for people with inherited blood disorders, certain rare diseases or who are undergoing chemotherapy.

But the field of transfusion medicine is changing. Instead of being viewed as an inert recharging of fluid, we are now coming to appreciate that a blood transfusion is essentially a liquid organ transplant, says National Blood Authority chair Leigh McJames; and like any other organ transplant, it has its risks.

The stuff of life

Australia has one of the safest blood supplies in the world, but that doesn’t mean blood transfusion is 100 per cent safe.

McJames says blood occupies a strange and somewhat privileged position in modern medicine, and that it has evolved as a treatment option without the same level of research scrutiny – at least on the patient outcomes side of things – that other treatments are subjected to.

“Nowadays if you have a modern pharmaceutical it goes through the whole bunch of clinical trials before it’s registered, but blood didn’t come to health that way,” he says.

But as far back as 1990, studies were hinting that blood transfusions carried more risks than had long been thought, says haematologist Professor James Isbister.

“It was becoming apparent that the mere fact you received a blood transfusion was a risk factor or was associated with poorer outcomes… in terms of increased length of stay in hospital, certain post-operative infections that weren’t directly from the transfusion, more likely to be ventilated, more likely to be intensive care,” says Isbister, Clinical Professor of Medicine at the University of Sydney Medical School.

Another clue that transfusions carried risks came from ‘restrictive transfusion’ studies done in otherwise stable patients, where the doctor was either instructed to give a transfusion only if a patient’s haemoglobin (the red protein in blood cells that carries oxygen) levels dropped to a certain point, or to treat as they normally would do.

“These trials have essentially all shown that a restrictive policy did not leave the patients any worse off and there is some evidence that they were better off,” Isbister says.

In a perfect world, scientists would do a clinical trial. People would be randomly be assigned to one of three groups – some would have a blood transfusion, others would be given a placebo and others no transfusion. Scientists would then compare how each group fared. But a trial such as this would never get approved, because why would you give a blood transfusion to someone who didn’t need one, even in a clinical trial setting? Conversely, why risk not giving blood to someone who might well die without it? Read more.

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