3.4 Effect of blood components on outcomes

3.4.3 Platelet transfusion

Evidence Statements for Platelet transfusion
Evidence Statements –
platelet transfusion
Evidence Consistency Clinical impact Generalisability Applicability
ES4.6 In patients with haematological malignancies receiving chemotherapy, the effect of prophylactic platelet transfusion on mortality is uncertain. X
ES4.7 In patients with haematological malignancies receiving chemotherapy, the effect of prophylactic platelet transfusion on bleeding events is uncertain. X NA
ES4.8 Platelet transfusions are associated with transfusion-related adverse events that can range from mild to serious. X
ES4.9 In a broad population of hospitalised cancer patients, platelet transfusion may be associated with increased mortality, but causation has not been established. X NA
ES4.10 In a broad population of hospitalised cancer patients, platelet transfusion may be associated with increased risk of thromboembolic events, but causation has not been established. X NA
ES4.11 In patients receiving chemotherapy and prophylactic platelet transfusion, the effect of platelet dose on mortality is uncertain. NA NA
ES4.12 In patients receiving chemotherapy and prophylactic platelet transfusion, platelet dose has no effect on bleeding events defined as mild or greater (WHO grade 2 or above). X
ES4.13 In patients receiving chemotherapy and prophylactic platelet transfusion, platelet dose does not appear to affect the incidence of transfusion-related adverse events.

ES, evidence statement; WHO, World Health Organization

=A; =B; =C; X=D; NA,not applicable (see Table 2.1)

Practice Points – platelet concentrates
PP20 Platelet transfusion may be indicated for the prevention and treatment of haemorrhage in patients with thrombocytopenia or platelet function defects. Platelet transfusions are not indicated in all causes of thrombocytopenia, and may be contraindicated in certain conditions (e.g. TTP and HIT). Thus, the cause of the thrombocytopenia should be established and expert opinion sought.
PP21

In patients with chronic failure of platelet production (e.g. myelodysplasia or aplastic anaemia), a specific threshold for transfusion may not be appropriate. These patients are best managed on an individual basis, in consultation with a relevant expert.9

Long-term prophylactic platelet transfusions may be best avoided because of the risk of complications (e.g. alloimmunisation and platelet refractoriness).

Therapeutic platelet transfusions could be considered for treatment of bleeding.

HIT, heparin-induced thrombocytopaenia; PP, practice point; TTP, thrombotic thrombocytopenic purpura

Platelet transfusion is a therapeutic intervention used for the prevention and treatment of bleeding in patients with thrombocytopenia or significant platelet dysfunction. The different methods for producing platelets result in differences in the final products (e.g. in dose and risk profile); this should be taken into account when comparing studies. The focus of this systematic review was to first compare prophylactic and therapeutic transfusion strategies, and then compare different platelet transfusion doses.

Prophylactic and therapeutic transfusion strategies

A small number of eligible studies were identified; all involved patients with cancer, including haematological malignancies. Thrombocytopenia was most commonly due to chemotherapy or stem cell transplantation. One additional study was a multivariate analysis of association between transfusions and venous thromboembolism, arterial thromboembolism and mortality in a broad population of hospitalised patients with cancer.90 No studies were found that included populations of special interest, such as patients receiving treatment with antifibrinolytic or antiplatelet therapy.

In patients with haematological malignancies receiving chemotherapy, mortality was reported in two studies: an RCT (Level II)131 that was inadequately powered to detect any clinically or statistically significant differences, and a cohort study (Level IV)132 that did not report any comparative data, but reported a mortality rate of 4.3% in patients receiving platelet transfusions.

The cohort study (Level III-2) in a broad population of hospitalised cancer patients90 found that platelet transfusion was independently associated with in-hospital mortality, and venous and arterial thromboembolism. This study controlled for a range of variables; however, as a cohort study, it could not establish causality.

Two studies reported the incidence of bleeding events. One RCT (Level II)133 reported no significant difference between study arms, and one cohort study (Level IV)132 found an incidence rate of 58.0% for grade 2 bleeding and 5.1% for grade 3 – 4 bleeding.

Four cohort studies reported the incidence of transfusion-related adverse events in patients receiving platelet transfusions.132,134-136 The incidences of adverse events ranged widely between studies. However, these discrepancies can probably be accounted for by differences in the study populations and the type of platelet product transfused.

Platelet transfusion doses

Five RCTs (Level II) assessed platelet dose in patients with haematological malignancies receiving chemotherapy.137-141 The definitions of thrombocytopenia and the assessed dose ranges varied widely between the studies. Mortality was reported in only one study;137 this study found no significant difference between any of the assessed platelet doses, but was underpowered.

Four studies reported the incidence of bleeding events. Slichter et al137 and Heddle et al138 found no significant difference between study arms in any of the dose comparisons presented. Tinmouth et al found a higher risk of experiencing a minor bleed in patients receiving three platelet units than five platelet units, but no significant difference between different platelet doses for the incidence of major bleeds.139 The study by Sensebé et al was underpowered to detect an effect of platelet dose on the incidence of haemorrhage.141

There was no significant difference between study arms in the two studies that reported the incidence of transfusion-related serious adverse events.132,137 However, the overall rate of serious adverse events was relatively high in both studies.