Prospective Multicenter Study of Viral Etiology and Hospital Length of Stay in Children With Severe Bronchiolitis

Objective: To determine whether hospital length of stay (LOS) for acute bronchiolitis is influenced by the infecting pathogen. Design: A prospective observational cohort study was performed during 3 consecutive years. Setting: Sixteen US hospitals participated in the study. Participants: Children younger than 2 years hospitalized with bronchiolitis were included. Main Exposure: The results of nasopharyngeal aspirate polymerase chain reaction pathogen testing served as the main exposure. Main Outcome Measure: Hospital LOS was determined. Results: Of 2207 participants, 72.0% had respiratory syncytial virus (RSV) and 25.6% had human rhinovirus (HRV); the incidence of each of the other viruses and bacteria was 7.8% or less. Multiple pathogen infections were present in 29.8% of the children. There were 1866 children (84.5%) with RSV and/or HRV. Among these 1866 children, the median age was 4 months and 59.5% were male. The median LOS was 2 days (interquartile range, 1-4 days). Compared with children who had only RSV, an LOS of 3 or more days was less likely among children with HRV alone (adjusted odds ratio [AOR], 0.36; 95% CI, 0.20-0.63; P < .001) and those with HRV plus non-RSV pathogens (AOR, 0.39; 95% CI, 0.23-0.66; P < .001) but more likely among children with RSV plus HRV(AOR, 1.33; 95% CI, 1.02-1.73; P =. 04), controlling for 15 demographic and clinical factors. Conclusions: In this multicenter study of children hospitalized with bronchiolitis, RSV was the most common virus detected, but HRV was detected in one-quarter of the children. Since 1 in 3 children had multiple virus infections and HRV was associated with LOS, these data challenge the effectiveness of current RSV-based cohorting practices, the sporadic testing for HRV in bronchiolitis research, and current thinking that the infectious etiology of severe bronchiolitis does not affect short-term outcomes.