Exploring the Value of sC5b-9 in the Diagnosis of Haematopoietic Stem Cell Transplant-Associated Thrombotic Microangiopathy in Children.

This study aims to explore the association between plasma human terminal complement complex C5b-9 (sC5b-9) levels and the occurrence of haematopoietic stem cell transplantation-associated thrombotic microangiopathy (TA-TMA) in children. The study retrospectively analysed the data of 131 patients who underwent allogeneic haematopoietic stem cell transplantation (allo-HSCT) at the Department of Haematology-Oncology between May 2020 and July 2023. The clinical data included dynamic data on plasma sC5b-9 concentrations and analysed the potential of pre- and post-transplantation levels for the prediction and diagnosis of TA-TMA after allo-HSCT. The median age of the cohort was 5.9 [3.4, 10.8] years, and it comprised 73 (55.8%) male and 58 (44.2%) female patients. The primary diseases were haematologic malignancy in 57 cases (43.5%), aplastic anaemia in 39 cases (29.8%) and Mediterranean anaemia in 13 cases (9.9%). Out of the 131 patients, 21 (14.7%) developed TA-TMA, and the median time of onset was 88 [59, 136] days after transplantation. The 1-year overall survival rate was significantly higher in the non-TA-TMA group (92.7% ± 2.5%) than in the TA-TMA group (47.6% ± 10.7%) (χ2 = 35.71, p < 0.05). During TA-TMA, sC5-9 levels are significantly elevated (p < 0.05). However, the baseline levels of sC5b-9 before allo-HSCT were not related to the development of TA-TMA after the procedure. The plasma sC5b-9 concentration after allo-HSCT in children is closely related to the occurrence of TA-TMA, and 306.4 ng/mL is an optimal clinical cut-off level above which TA-TMA is indicated. This cut-off level was associated with a sensitivity of 90.5% and a specificity of 86.6%. Nonetheless, the diagnosis of TA-TMA should be established in conjunction with clinical manifestations and corroborated by additional laboratory test results.