Incidence, risk factors and clinical outcomes of primary prolonged isolated thrombocytopenia following haploidentical transplantation for severe aplastic anemia.

Abstract

While primary prolonged isolated thrombocytopenia (PT) represents a common complication after haploidentical hematopoietic stem cell transplantation (haplo-HSCT), its clinical significance in severe aplastic anemia (SAA) patients remains underexplored. This study aims to characterize the incidence, prognostic impact and risk factors of PT in SAA patients undergoing haplo-HSCT. The authors retrospectively analyzed the clinical data of 502 patients diagnosed with SAA who underwent haplo-HSCT at our institution between January 2006 and December 2022. The cumulative incidence of primary PT was 7.6% (38/502). Primary PT significantly correlated with inferior long-term outcomes, demonstrating markedly reduced 5-year overall survival (65.8% vs. 94.1%, P < 0.001) and graft-versus-host disease (GvHD)-free, failure-free survival (44.7% vs. 83.3%, P < 0.001) compared to non-PT counterparts. Multivariate analysis revealed five independent risk factors: pretransplant red blood cell transfusion burden ≥40 units, maternal donor, infused CD34⁺ cell dose <2 × 10⁶/kg, grade II-IV acute GvHD and refractory cytomegalovirus viremia. A risk stratification model incorporating these factors showed discriminative capacity, with primary PT incidence escalating from 2.3% (low-risk: 0 factors) to 6.9% (intermediate-risk: 1-2 factors) and 31.7% (high-risk: 3-5 factors) (P < 0.001). This study establishes primary PT as an independent prognostic marker in SAA patients receiving haplo-HSCT. The developed risk model may facilitate early identification of high-risk patients requiring intensified monitoring and preemptive interventions.