Appendix B Transfusion risks in the context of patient blood management

Traditionally, it has been assumed that blood transfusion benefits patients; however, a benefit has not been demonstrable in many clinical scenarios. In addition, evidence is accumulating that serious non- viral adverse events, such as transfusion-associated circulatory overload (TACO) or transfusion-related acute lung injury (TRALI), are more common than previously thought, and that more recently identified conditions (e.g. transfusion-related immunomodulation) may cause patients harm.

The risk of transmission of infectious diseases through blood transfusions has reduced significantly in recent years, through improved manufacturing and laboratory processes. However, there is potential for transfusion of an unrecognised infectious agent.

Despite improvements in systems management, there remains a risk of transfusion-related harm due to administrative error. Such an error has the potential to result in acute haemolytic reaction from ABO incompatibility, which may be fatal.

If the patient requires therapy for anaemia, thrombocytopaenia or coagulopathy, transfusion should not be a default decision. Instead, the decision on whether to transfuse should be carefully considered, and should:

take into account the full range of available therapies
balance the evidence for efficacy and improved clinical outcome against the risks
take into account patient values and choices

In the process of obtaining informed consent, a clinician should allow the patient sufficient time to ask questions, and should answer those questions. If the patient is unable to speak or understand English, the clinician may need to involve an interpreter. In certain contexts, a trained medical interpreter may be required (rather than a family member or a friend). Written information and diagrams may be appropriate in certain circumstances to aid understanding.

All elements of the consent process should reflect local state, territory or national requirements.

Table B.1 summarises transfusion risks, and Table B.2 presents the Calman Chart, which may be useful to clinicians for explaining risks to patients.¹⁷⁷

Table B.1 Transfusion risks
TRANSFUSION RISK	ESTIMATED RATE^a (HIGHEST TO LOWEST RISK)	CALMAN RATING^b
Transfusion-associated circulatory overload (iatrogenic)	Up to 1 in 100 transfusions	High
Transfusion-related acute lung injury	1 in 1200 – 190,000	Low to minimal
Haemolytic reactions	Delayed: 1 in 2500 – 11,000 Acute: 1 in 76,000 Fatal: Less than 1 in 1 million	Low to very low Very low Negligible
Anaphylactoid reactions or anaphylaxis (usually due to IgA deficiency)	1 in 20,000 – 50,000	Very low
Bacterial sepsis: platelets	1 in 75,000	Very low
Bacterial sepsis: red blood cells	1 in 500,000	Minimal
Hepatitis B	Less than 1 in 1 million	Negligible
Hepatitis C	Less than 1 in 1 million	Negligible
Human immunodeficiency virus	Less than 1 in 1 million	Negligible
Human T-lymphotropic virus (types 1 and 2)	Less than 1 in 1 million	Negligible
Malaria	Less than 1 in 1 million	Negligible
Variant Creutzfeldt-Jakob disease (not tested)	Never reported in Australia	Negligible
Transfusion-associated graft-versus-host disease	Rare	Negligible
Transfusion-related immunomodulation	Not quantified	Unknown

^a Risk per unit transfused unless otherwise specified

^b See Calman 1996¹⁷⁷

Source: Australian Red Cross Blood Service website (www.transfusion.com.au)

Note: The above estimates may change over time. Refer to the Australian Red Cross Blood Service website (www.transfusion.com.au) for the most recent risk estimates.

Table B.2 Calman Chart^a (United Kingdom risk per one year)
RATING	RATE	EXAMPLE
Negligible	<1 in 1,000,000	Death from lightning strike
Minimal	1 in 100,000 – 1,000,000	Death from train accident
Very low	1 in 10,000 – 100,000	Death from an accident at work
Low	1 in 1,000 – 10,000	Death from a road accident
High	>1 in 1,000	Transmission of chicken pox to susceptible household contacts

^a See Calman 1996¹⁷⁷