Decreased lymphocyte count before conditioning is associated with BK virus-associated hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation

BK virus-associated hemorrhagic cystitis (BKV-HC) is a serious complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). It can cause morbidity and may increase treatment-related mortality. Previous studies showed that the occurrence of BKV-HC was related to various factors. However, there are still many controversial factors. It is not clear whether BKV-HC will affect the long-term prognosis of patients.We aimed to identify risk factors for BKV-HC after allo-HSCT and evaluate the effect of BKV-HC on overall survival (OS) and progression- free survival (PFS) of patients.We retrospectively analyzed the clinical data of 93 patients who underwent allo-HSCT. Univariate and multivariate analysis were used to identify risk factors for BKV-HC. The Kaplan-Meier method was used to estimate OS and PFS. A difference was considered statistically significant if P < 0.05.A total of 24 patients developed BKV-HC. The median occurrence time of BKV-HC was 30 (range:8-89) days after transplantation, and the median duration was 25.5 (range:6-50) days. Multivariate logistic regression analysis indicated that peripheral blood lymphocyte count <1 × 109/L before conditioning (OR = 4.705, P = 0.007) and haploidentical transplantation (OR = 13.161, P = 0.018) were independent risk factors for BKV-HC. The 3-year OS rate was 85.9% (95%CI:62.1%-95.2%) in the BKV-HC group and 73.1% (95%CI: 58.2%-88.0%) in the non-BKV-HC group. There was no significant difference between the two groups (P = 0.516). The 3-year PFS rate was 76.3% (95%CI: 57.9%-94.7%) in the BKV-HC group and 58.1% (95%CI: 39.5%-76.7%) in the non-BKV-HC group. There was no significant difference in the two groups (P = 0.459). The severity of BKV-HC was not related to the OS and PFS of the patients (P value was 0.816 and 0.501, respectively).Haploidentical transplantation and decreased peripheral blood lymphocyte count before conditioning increased the risk of BKV-HC after allo-HSCT. The occurrence of BKV-HC after allo-HSCT and the severity of which did not affect OS and PFS of the patients.