title: Influenza and other respiratory virus-related emergency department visits among young children.
abstract: BACKGROUND
  Influenza and other winter respiratory viruses cause substantial morbidity among children. Previous estimates of the burden of illness of these viruses have neglected to include the emergency department, where a large number of patients seek acute care for respiratory illnesses. This study provides city- and statewide population estimates of the burden of illness attributable to respiratory viruses for children receiving emergency department-based care for respiratory infections during the winter months.
  
  
  METHODS
  The number of patients < or = 7 years of age presenting to the emergency department of an urban tertiary care pediatric hospital with acute respiratory infections was estimated by using a classifier based on presenting complaints. The rates of specific viral infections in this population were estimated by using the rates of positivity for respiratory syncytial virus, influenza virus, parainfluenza virus, adenovirus, and enterovirus. Local emergency department market share and US Census data enabled determination of the rates of emergency department visits in the Boston, Massachusetts, area and in Massachusetts.
  
  
  RESULTS
  During the 11-year study period, the mean yearly number of patients < or = 7 years of age presenting to the study emergency department during the winter season was 17397. On the basis of the respiratory classifier, the mean number of patients with an acute respiratory infection was 6923, or 398 per 1000 emergency department visits. In the city population, the mean number of emergency department visits for acute respiratory infections was 17906, which is equivalent to 113.9 per 1000 children residing in the city, and in the state population the mean number was 61529, or 94.5 per 1000 children residing in the state. At the state level, 23114 of the visits were for respiratory syncytial virus, 5650 for influenza, 1751 for parainfluenza virus, 2848 for adenovirus, and 798 for enterovirus. For patients 6 to 23 months of age in the state population, there were 19860 emergency department visits for acute respiratory infections, or 168 per 1000 children in this age group, with 6235 visits resulting from respiratory syncytial virus and 2112 resulting from influenza.
  
  
  CONCLUSIONS
  There is a high incidence of emergency department visits for infectious respiratory illnesses among children. This important component of health care use should be included in estimates of the burden of illness attributable to influenza and other winter respiratory viruses.
authors.affiliation: Division of Emergency Medicine, Children's Hospital Boston, 300 Longwood Ave, Boston, Massachusetts 02115, USA. florence.bourgeois@childrens.harvard.edu
authors.forename: Florence T
authors.initials: FT
authors.lastname: Bourgeois
authors.forename: Clarissa
authors.initials: C
authors.lastname: Valim
authors.forename: Jennie C
authors.initials: JC
authors.lastname: Wei
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: McAdam
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Mandl
mesh_terms: D001900:Boston / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D017281:Cost of Illness; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology; D012189:Retrospective Studies; D012621:Seasons