ORLANDO – For patients who have received hematopoietic cell transplants, a rhinovirus infection can become much more than a cold.
“It holds true that rhinovirus is just as likely to be associated with mortality as are other respiratory viruses” among HCT recipients, Alpana Waghmare, MD, said at the combined annual meetings of the Center for International Blood & Marrow Transplant Research and the American Society for Blood and Marrow Transplantation.
In a new retrospective study, Dr. Waghmare and her coinvestigators found that the median time for a rhinovirus infection to progress from an upper to a lower respiratory tract infection was about 2 weeks among post-HCT patients.
Clinical and demographic risk factors for progression to lower respiratory tract infection included higher levels of steroid use (2 mg/kg per day or more) before developing the upper respiratory infection, a low white blood cell count, and a low monocyte count, said Dr. Waghmare, an infectious disease specialist and professor of pediatrics at the University of Washington, Seattle.
Of 3,445 HCT patients treated at the university center during the 6-year study, 732 patients (21%) were positive for human rhinovirus. Patients were classified as having upper respiratory infections if they had a PCR-positive nasal swab.
Patients were classed in one of three categories for potential lower respiratory infections: Proven lower respiratory infections were those detected by bronchoalveolar lavage or biopsy in patients who had a new radiographic abnormality. Probable lower respiratory infections were those with positive findings on bronchoalveolar lavage or biopsy but without radiographic changes. In possible lower respiratory infections, patients had upper tract virus detected on nasal swabs but did have a new radiographic abnormality.
Among the patients positive for human rhinovirus, 85% (665 patients) presented with upper respiratory infections and 15% (117 patients) with lower respiratory tract infections. By day 90, 16% of patients progressed from upper to lower respiratory tract infections. The median time to progression was 13.5 days. Progression to proven lower respiratory tract infection affected 5% of the HCT recipients.
In multivariable analytic models, a minimum white blood cell count of 1,000 or less was associated with a hazard ratio (HR) of 2.21 for progression to lower respiratory tract infection. A minimum monocyte count of 1,000 or less was associated with a HR of 3.66 for progression to lower respiratory tract infection.
The model also found a HR of 3.37 for lower respiratory tract infection with steroid use of 2 mg/kg per day or more. The patient’s conditioning regimen and donor type were not significantly associated with risk of progression to lower respiratory infection.
Viral copathogens, prior respiratory virus episodes, and the duration of time since HCT were not associated with risk of progress to lower respiratory infections. Neither were patient age, baseline lung function, and the year the transplant occurred.
“These data provide an initial framework for patient risk stratification and the development of rational prevention and treatment strategies in HCT recipients,” she said.
Dr. Waghmare reported receiving research funding from Aviragen, the maker of vapendavir, an investigational drug for human rhinovirus infection, and Gilead Sciences.
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