Classification and incidence of adverse events

It’s important to recognise, respond to and report suspected adverse events.

Once you suspect an adverse reaction, follow the steps for managing suspected transfusion reactions.

Classification of transfusion-related adverse reactions and estimated incidence

Immunological acute (<24 hours)

Adverse event	Incidence*
Acute haemolytic transfusion reaction (AHTR)	1:76,000
Fatal acute haemolytic reaction	1:1.8 million
Febrile non-haemolytic transfusion reaction (FNHTR)	0.1%–1% (with universal leucocyte depletion)
Mild allergic reactions (urticarial)	1%–3%
Severe allergic reactions (anaphylaxis)	1:20,000–1:50,000
Transfusion-related acute lung injury (TRALI)	1:1,200–1:190,000

Non-immunological acute (<24 hours)

Adverse event	Incidence*
Complications of massive transfusion	Variable
Non-immune mediated haemolysis (physical or chemical destruction of blood)	Rare
Transfusion transmitted bacterial infection (for clinically apparent reactions) due to platelets	Approximately 1:250,000 (in Australia)
Transfusion transmitted bacterial infection (for clinically apparent reactions) due to red cells	Approximately 1:2.5 million (in Australia)
Transfusion-associated circulatory overload (TACO)	1%

Immunological delayed (>24hours)

Adverse event	Incidence*
Delayed haemolytic transfusion reaction (DHTR)	1:2,500–1:11,000
Post-transfusion purpura (PTP)	Rare
Transfusion-associated graft versus host disease (TA-GVHD)	Rare
Alloimmunisation - RBC antigens	1%
Alloimmunisation - HLA antigens	10%
Transfusion-related immune modulation (TRIM)	Not known

Non-immunological delayed (>24hours)

Adverse event	Incidence*
Iron overload requiring chelation therapy	May occur after >20 RBC units
Iron overload with organ dysfunction	May occur after 50-100 RBC units
Transfusion-transmissible infections	For incidence rates refer to risk estimates for transfusion-transmissible infections