BOSTON – Coinfections with both respiratory syncytial virus and rhinovirus were common and associated with increased length of stay in a prospective multicenter study of over 2,000 children under 2 years of age who were hospitalized with bronchiolitis.
The clinical value of testing for an infectious etiology in a child with bronchiolitis is unclear. Indeed, the recommendation is not to test (Pediatrics 2006;118:1774-93). Some argue however, that testing may be useful for the influenza treatment or to identify the beginning of the viral "seasons" and which viruses are circulating, Dr. Jonathan M. Mansbach, a hospitalist physician at Children’s Hospital Boston, said at the annual meeting of the Society for Academic Emergency Medicine.
Photo credit: © Dr. Craig Lyerla / CDC
Respiratory syncytial virus (shown here using indirect immunofluorescence) is the most common cause of bronchiolitis and pneumonia among infants and children under 1 year of age. The majority of children hospitalized for RSV infection are under 6 months of age.
Additionally, Dr. Mansbach said that the 70% frequency of coinfection seen in this study raises questions about the effectiveness of inpatient cohorting by viral etiology, which some researchers contend is of use. Moreover, the findings suggest that hospitals consider adding RV to respiratory viral panels, he said.
The 16-center study enrolled consecutive children between November and March during 2007-2010. Of the total 2,207 children enrolled, 83% were located on the ward while 17% were admitted to the intensive care unit. Of those 377, 42% were intubated or given continuous positive airway pressure. Overall mean length of stay was 2 days. The patients had a median age of 4 months; 59% were male, 61% were white, 24% black, and 15% other races. A third (36%) were of Hispanic ethnicity.
The three most common viral etiologies identified by polymerase chain reaction were RSV-A (43%) RSV-B (30%) and RV (26%). Adenovirus, human metapneumovirus, and the coronaviruses were all 7%-8%, and only 6% of the children had no virus detected. (These figures add up to more than 100 because of a 30% rate of coinfections.) The low-frequency infections did not affect results, so subsequent analysis focused on RSV (subtypes A and B) and RV, Dr. Mansbach said.
Of the 940 children in whom RSV-A was identified, it was the only virus in 66%, while one or more additional viruses were identified in the other 34%. Similarly, 68% of the 664 RSV-B infected patients had only one virus identified, while 32% were coinfected.
Rhinovirus was somewhat different, however, in that just 30% of 564 had only that and 70% had coinfections.
For children with both RSV-A and RSV-B, the likelihood of having a length of stay of 3 or more days did not differ between those who had the single virus infection and those who were coinfected (48% vs. 49%, respectively, for RSV-A, and 47% and 54% for RSV-B). There was a significant difference with rhinovirus, however, with 28% of those with the single infection and 46% with coinfections hospitalized 3 or more days.
After adjustment for age, gender, race, eczema history, intubation history, apnea, retractions, oxygen saturation, oral intake, comorbid medical condition, and site, rhinovirus alone was associated with a lower chance of being hospitalized 3 or more days compared with RSV-A or RSV-B alone (odds ratio 0.4), while RSV-RV co-infections were associated with a significantly greater chance of being hospitalized for that duration compared with RSV-A or RSV-B alone (OR 1.3).
Clustering by site did not affect the results, and in a preliminary analysis, controlling for acute severity as defined by ICU, CPAP, or intubation also did not materially change the results, Dr. Mansbach said.
This study was conducted as part of the Multicenter Airway Research Collaboration (MARC), a program of the Emergency Medicine Network. Pediatric Research in Inpatient Settings sites collaborated with EMNet, Dr. Mansbach said.
Dr. Mansbach stated that he had no relevant financial disclosures.