Data published in the Journal of Infectious Diseases suggest that host and transplant-related factors determine the risk of progression to lower respiratory tract disease among hematopoietic cell transplant recipients with respiratory syncytial virus, whereas viral factors are less important.
“Knowledge of risk factors can help identify high-risk patients that may benefit most from early antiviral treatment,” Michael Boeckh, MD, of the Fred Hutchinson Cancer Research Center, Vaccine and Infectious Disease Research Center, told Infectious Disease News. “The highly significant role of lymphopenia seen in this and other studies suggests that dysfunctional cell-mediated immunity appears to be important in the pathogenesis of progressive RSV disease within the first 3 months after hematopoietic cell transplant (HCT).”
Boeckh and colleagues conducted a retrospective analysis to evaluate several risk factors for progression to lower respiratory tract disease in this patient group. The study included 181 HCT recipients who had RSV upper respiratory tract infections. The patients underwent their transplants from November 1988 to June 2011.
Among the 181 patients in the study, 43 (24%) progressed from upper respiratory tract infection to lower respiratory tract infection. RSV upper respiratory tract infections occurred at median post-transplant day 49, and progression to lower respiratory tract infection occurred at a median of 7 days after upper respiratory tract infection.
In a multivariable model that included 175 patients with 41 of those who progressed, smoking, high-dose total body irradiation and an absolute lymphocyte count of 100/mm3 or less at diagnosis of RSV upper respiratory tract infection were significant risk factors for progression to lower respiratory tract infection. There were no statistically significant effects of high-dose ribavirin treatment, corticosteroid dose or RSV subtype on progression to lower respiratory tract infection. Lymphocyte engraftment dynamics and pre- and post-transplant donor and post-transplant recipient neutralizing antibody levels also were not associated with progression to lower respiratory tract infection.
“This study identified a protective lymphocyte count level (more than 1,000/mm3), which might suggest that patients who acquire RSV during the first 100 days after transplantation do not require treatment if they have good lymphocyte counts,” Boeckh said. “On the other hand, patients with the risk factors identified in this study may be good candidates for early antiviral treatment.” – by Emily Shafer
Michael Boeckh, MD, can be reached at email@example.com.
Disclosure: Boeckh has received research funding from ADMA Pharmaceuticals and GlaxoSmithKline and has served as a consultant for Gilead and GlaxoSmithKline.