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V. Brixner et al.
Figure 1. CAPTURE/CONSORT study flow diagram. Off-protocol platelet transfusions were defined as transfusions of conventional platelet units, and treatment errors were defined as transfusions with study platelet products from the wrong treatment arm.
reduced platelets produced by THERAFLEX UV-Platelets PR technology in thrombocytopenic patients with hema- tologic or oncologic malignancies. One-hour CCI was fre- quently used as a primary or secondary outcome in previ- ous clinical studies with standard and pathogen-reduced platelets.17-26 With one exception,24 the transfusion of pathogen-reduced platelets in these studies resulted in a reduction of mean 1-hour CCI, ranging from 12% to 31% for amotosalen/UVA-treated PC and from 30% to 38% for riboflavin/UV-treated PC. Based on these findings obtained with two alternative PR methods, we set the non-inferiority margin for the mean 1-hour CCI at 30%. This margin is supported by the result of the PLADO trial investigating single transfusions with platelet doses between 1.1x1011 and 4.4x1011 per square meter of body- surface area in the prophylactic transfusion setting.26 The median 4-hour post transfusion CCI in the low dose platelet group of PLADO was 10 (interquartile range, 5-15)
and in the medium dose group also 10 (interquartile range, 6-16). The frequency and severity of bleeding events (WHO grade ≥2) in both groups were not higher than that in patients in the high dose group. With a mean platelet dose of 1.7x1011/m2 in pathogen-reduced PC in our trial, a CCI reduction by 30% corresponds to a mean dose of 1.2x1011/m2 which is still within the range of the PLADO trial. The about 18% lower mean 1-hour CCI, which is very consistent with the result of a radiolabeling study,16 and the 19% lower mean 24-hour CCI in our study sug- gest a reduced transfusion efficacy for UVC-treated platelets compared to untreated platelets. There are other product-related factors such as the use of a platelet addi- tive solution (PAS) and γ-irradiation that also affect CCI outcome.24,27 In our study, UVC-treated platelets were gen- erally not γ-irradiated and PAS was used for preparation of both test and control platelet units. Therefore, the lower CCI for UVC-treated platelet transfusions are likely due to
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haematologica | 2021; 106(4)