The haematopoietic cell transplantation comorbidity index predicts clinical outcomes for severe aplastic anaemia patients after haploidentical haematopoietic stem cell transplantation

To validate the ability of the haematopoietic cell transplantation comorbidity index (HCT-CI) to predict the outcomes of patients with severe aplastic anaemia (SAA) receiving haploidentical haematopoietic stem cell transplantation (haplo-HSCT), we conducted a retrospective study including 530 SAA patients. Patients were stratified based on their HCT-CI scores into three distinct risk categories: low-risk (HCT-CI scores of 0, n = 343), intermediate-risk (HCT-CI scores of 1, n = 126), and high-risk groups (HCT-CI scores ≥ 2, n = 61). The 100-day platelet engraftment rate was significantly higher in the low-risk group compared to the intermediate-risk and high-risk groups (92.1% vs. 86.5% vs. 83.6%, P = 0.014). In addition, compared with the intermediate-risk and high-risk groups, the low-risk group demonstrated superior 5-year overall survival (OS, 91.8% vs. 83.3% vs. 70.1%, P < 0.001) and graft-versus-host disease-free/graft failure-free survival (GFFS, 80.1% vs. 71.3% vs. 63.6%, P = 0.009). Multivariate analysis revealed that elevated HCT-CI scores and previous antithymocyte globulin treatment were independent risk factors for OS, whereas elevated HCT-CI scores and donor age ≥ 40 years were correlated with worse GFFS. Consequently, the HCT-CI is associated with the clinical outcomes of SAA patients following haplo-HSCT, and it is imperative to closely monitor patients with a high comorbidity burden.