Clinical impact and predisposing factors of delayed-onset neutropenia after autologous hematopoietic stem-cell transplantation for B-cell non-Hodgkin lymphoma: association with an incremental risk of infectious events.

BACKGROUND Clinical significance of delayed-onset neutropenia (DON) after autologous hematopoietic stem-cell transplantation (ASCT) has not been well described. We conducted a retrospective cohort study to examine risk factors and clinical impact of DON. DESIGN AND METHODS Subjects were consecutive 108 patients with B-cell lymphoma receiving ASCT. We defined DON as absolute neutrophil counts <1.0 x 10(9)/l at any point from 30 days onward after ASCT without apparent causes of neutropenia. Documented infectious events were reviewed from 1 to 18 months after ASCT. RESULTS Fifty-two percent of patients received rituximab. Cumulative incidence of DON was 50% at 1 year. Rituximab usage was identified as an independent risk factor of DON. A total of 117 infectious events were documented, of which 24 events occurred during DON period. Cumulative incidence of total infectious events was 75% and 42% in the groups with and without DON, respectively (P = 0.001). Varicella-zoster virus (P = 0.033) and upper respiratory infection (P = 0.016) were frequent in the patients experiencing DON. In a multivariable analysis, DON remained a significant factor for total infectious events and upper respiratory infection. CONCLUSIONS Rituximab usage is an independent risk factor of DON. DON correlates with increased occurrence of infectious events. Careful follow-up would be needed after the onset of DON.