Safety of blood transfusion improved by the use of 'transfusion thresholds'

Many people are given a transfusion of blood from an unrelated donor as part of their medical treatment. There are, however, risks involved. In particular, infections (including HIV and certain types of hepatitis) may be passed on to the person receiving the blood. This risk is small in high income countries but much larger in poor countries which lack good facilities to test the blood for infections. Because of the risks, doctors try to avoid giving blood unless it is really necessary. One approach is to give the transfusion only if the amount of haemoglobin in the patient's blood has dropped below a certain 'threshold' level. The authors looked for controlled studies evaluating the effectiveness of this approach. They found 17, with a total of 3746 patients. The authors say that more research is needed and that, until more is known, patients who have a serious heart problem should not be treated in this way. The authors conclude that, for most patients, blood transfusion is probably not essential until haemoglobin levels drop below 7.0 grammes per decilitre.