title: Multicenter study of viral etiology and relapse in hospitalized children with bronchiolitis.
abstract: BACKGROUND
  It is unclear whether the infectious etiology of severe bronchiolitis affects short-term outcomes, such as posthospitalization relapse. We tested the hypothesis that children hospitalized with rhinovirus (RV) bronchiolitis, either as a sole pathogen or in combination with respiratory syncytial virus (RSV), are at increased risk of relapse.
  
  
  METHODS
  We performed a 16-center, prospective cohort study of hospitalized children age <2 years with bronchiolitis. During the winters of 2007-2010, researchers collected clinical data and nasopharyngeal aspirates from study participants; the aspirates were tested using real-time polymerase chain reaction. The primary outcome was bronchiolitis relapse (urgent bronchiolitis visit or scheduled visit at which additions to the bronchiolitis medications were made) during the 2 weeks after hospital discharge.
  
  
  RESULTS
  Among 1836 enrolled children with 2-week, follow-up data, the median age was 4 months and 60% were male. Overall, 48% had sole RSV infection, 8% had sole RV infection, and 13% had RSV/RV coinfection. Compared with children with sole RSV infection, and adjusting for 10 demographic and clinical characteristics and clustering of patients within hospitals, children with sole RV infection did not differ in their likelihood of relapse (odds ratio: 0.99; 95% confidence interval: 0.52-1.90; P = 0.98), whereas those with RSV/RV coinfection were more likely to have relapse (odds ratio: 1.54; 95% confidence interval: 1.03-2.30; P = 0.03).
  
  
  CONCLUSIONS
  In this prospective, multicenter, multiyear study of children hospitalized with bronchiolitis, we found that RSV/RV coinfection was independently associated with a higher likelihood of bronchiolitis relapse. Present data support the concept that the infectious etiology of severe bronchiolitis affects short-term outcomes.
authors.affiliation: From the *Department of Emergency Medicine, Massachusetts General Hospital; †Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA; ‡Division of Emergency Medicine, Children's National Health System, Washington, DC; §Department of Pediatrics, Rady Children's Hospital, University of California San Diego, San Diego; ¶Division of Hospital Medicine, Children's Hospital Los Angeles, Los Angeles, CA; ‖Department of Emergency Medicine, Weill Cornell Medical College, New York, NY; and **Departments of Molecular Virology and Microbiology, and Pediatrics, Baylor College of Medicine, Houston, TX.
authors.forename: Kohei
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Mansbach
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Teach
authors.forename: Erin S
authors.initials: ES
authors.lastname: Fisher
authors.forename: Daniel
authors.initials: D
authors.lastname: Hershey
authors.forename: Joyce Y
authors.initials: JY
authors.lastname: Koh
authors.forename: Sunday
authors.initials: S
authors.lastname: Clark
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Piedra
authors.forename: Ashley F
authors.initials: AF
authors.lastname: Sullivan
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
mesh_terms: D001988:Bronchiolitis / Q000453:epidemiology* / Q000821:virology*; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015999:Multivariate Analysis; D010850:Picornaviridae Infections / Q000453:epidemiology / Q000821:virology; D011446:Prospective Studies; D012008:Recurrence; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000821:virology; D018113:Respiratory Syncytial Virus, Human / Q000302:isolation & purification; D012229:Rhinovirus / Q000302:isolation & purification; D014481:United States / Q000453:epidemiology