Correlation of initial upper respiratory tract viral burden with progression to lower tract disease in adult allogeneic hematopoietic cell transplant recipients.

BACKGROUND: Some respiratory viruses have been evaluated for the association between viral burden and respiratory disease progression in hematopoietic cell transplant (HCT) recipients, and no significant association has been reported.
OBJECTIVES: To assess whether initial viral burden of respiratory viruses predicts risk of progression to lower respiratory tract infection (LRTI) among adult allogeneic HCT recipients who presented with upper respiratory tract infection (URTI) with 12 viruses in the PCR era. STUDY
DESIGN: We reviewed adult allogeneic HCT recipients (4/2008-9/2018) who presented with their first symptomatic respiratory viral infection following transplantation at the Fred Hutchinson Cancer Center. Cox proportional hazards models were used to investigate whether viral burden as measured by initial Ct values at the diagnosis of URTI is associated with progression to LRTI within 90 days for each virus, treating death as a competing risk.
RESULTS: Among 2,148 adult HCT recipients during the study periods, 1,102 episodes of URTI met the study inclusion criteria. Higher viral burden (lower Ct value) were associated with an increased risk of progression to LRTI for influenza after adjusting for immunodeficiency scoring index and initiation of antiviral therapy, respectively. The association between viral burden and progression to LRTI was not found for other viruses.
CONCLUSIONS: Our findings suggest that routine reporting of viral burden in current molecular diagnostic platforms may be beneficial. Further studies are needed to investigate the impact of viral burden on LRTI in other populations including pediatric HCT recipients.