A contribution to the indications for platelet transfusion and determination of its therapeutic efficacy.

Abstract The platelet count does not really reflect the true bleeding risk in chronically thrombocytopenic patients. Recently, we reported on two modifications of an in vitro bleeding test (IVBT) which appeared to be suitable for the evaluation of primary non-vascular hemostatis in thrombocytopenic and anemic patients (platelets 10–50,000/μL, hct 16–30 L/L). We report on the clinical study conducted with the IVBT modification which proved to be superior. Fifty thrombocytopenic patients, 42 with bone marrow hypoplasia and 8 with autoimmune thrombocytopenia, were followed up for a total of 686 days and received 161 platelet transfusions (mainly from cell separator). The IVBT was carried out with the Thrombostat 4000 R in triplicate using 120 μm filters and evaluating the occlusion time (OT). Additionally, cell count, hematocrit, body temperature, platelet volume, platelet distribution width, Simplate R time and a detailed analysis of bleeding signs for the calculation of a bleeding score were performed. The IVBT modification used allowed the determination of platelet-related bleeding risk in thrombocytopenic patients. With the IVBT, significant differences in platelet function in different patients could be demonstrated which primarily reflected the underlying disease. In addition, bone marrow regeneration correlated with platelet function. From the findings of this study, the authors formulate criteria for the indication of platelet transfusion which includes platelet function as well as the platelet count. Increased individual bleeding risk factors have to be considered too. But before generalization these criteria have to be verified by a controlled prospective study. In addition, the IVBT was well suited to prove the efficacy of platelet transfusions. On the other hand, the test still involves too much labor and cost for routine application. The next generation of equipment and improved disposables should solve these problems.