Immunoplatelet counting: potential for reducing the use of platelet transfusions through more accurate platelet counting

Abstract

Summary. Research is required to determine the optimal approach for prophylactic platelet transfusions in patients with haematological malignant disorders. It has been suggested that thresholds for prophylactic platelet transfusions of platelet counts below 10 × 109/l should be investigated, as these may be equivalent in clinical effectiveness and associated with lower costs and fewer complications. An important concern in such investigation is the accurate estimation of platelet counts below 10 × 109/l. This study aimed to further examine the potential reduction in platelet usage that could be made if a lowered platelet transfusion threshold of 5 × 109/l was used in conjunction with an immunoplatelet counting method. Clinical and laboratory data from 130 haematology patients were used. Standard platelet counting was performed using Bayer H3 and ABX Argos analysers. Immunoplatelet counting was performed by flow cytometry using anti‐CD61. The potential for reducing platelet transfusions included consideration of clinical criteria that influence prophylactic platelet transfusion use. The results indicated that the use of an immunoplatelet count with a 5 × 109/l platelet transfusion threshold would potentially reduce the number of transfusions by 10·4% in comparison with a 10 × 109/l threshold and standard automated platelet counting with the ABX Argos analyser, and increase the number of transfusions by 5·4% in comparison with the same threshold using the Bayer H3 analyser. The immunoplatelet count may aid the clinical decision to transfuse platelets, but would not necessarily lead to a reduced use of platelet transfusions.

Counting platelets in platelet concentrates on hematology analyzers: a multicenter comparative study

“…Accuracy of a method can be determined by comparing the results of a particular analyzer with those obtained with a gold standard counting method. By definition, this status is currently assigned to a method based on staining PLTs with fluorescent conjugated CD61 antibodies and subsequent detection usually with a flow cytometer 10,12,13 . Because the sample is continuously diluted with sheath fluid, the exact sample volume that is counted is not known, and therefore RBCs are counted simultaneously.…”

Impact of immunological platelet counting (by the platelet/RBC ratio) on haematological practice

“…They concluded that an accurate count (the reference method) in conjunction with a platelet transfusion threshold of 5 Â 10 9 /L could potentially decrease the number of platelet transfusions by 10.4%. However, conflicting results were obtained at higher thresholds and the investigators concluded that larger well-designed multicentre studies were required (11). The same group recently reported a multicentre evaluation of all currently available technologies in the United Kingdom (see below) (12).…”

“…The investigators suggested that the patient population, sample selection, and reference method may have contributed to the discordance between this study and other evaluations (10). Another independent laboratory also utilised the RBC/platelet ratio and were confident to use this as a reference method for the comparison of Bayer and ABX counters (11). They concluded that an accurate count (the reference method) in conjunction with a platelet transfusion threshold of 5 Â 10 9 /L could potentially decrease the number of platelet transfusions by 10.4%.…”

The Accuracy of Platelet Counting in Thrombocytopenic Blood Samples Distributed by the UK National External Quality Assessment Scheme for General Haematology

“…1 This reduction would conserve valuable stocks of platelets for transfusion and reduce the exposure of patients to the risks associated with transfusion of blood components. The accuracy of platelet counts produced by routine automated hematology analyzers has been questioned, [2][3][4] and the limitations of platelet counting at these extremely low levels should be understood by people responsible for the care of patients.…”