title: Complications and associated bacterial coinfections among children hospitalized with seasonal or pandemic influenza, United States, 2003-2010.
abstract: BACKGROUND
  Data on the range and severity of influenza-associated complications among children are limited. We describe the frequency and severity of complications in hospitalized children aged <18 years with seasonal influenza (during 2003-2009) and 2009 pandemic influenza A(H1N1) (during 2009-2010).
  
  
  METHODS
  Population-based surveillance for laboratory-confirmed influenza hospitalizations was conducted among 5.3 million children in 10 states. Complications were identified by International Classification of Diseases, Ninth Revision (ICD-9) codes in medical records.
  
  
  RESULTS
  During 2003-2010, 7293 children hospitalized with influenza were identified, of whom 6769 (93%) had complete ICD-9 code data. Among the 6769 children, the median length of hospitalization was 3 days (interquartile range, 2-4 days), 975 (14%) required intensive care, 359 (5%) had respiratory failure, and 40 (1%) died. The most common complications were pneumonia (in 28% of children), asthma exacerbations (in 22% [793/3616] aged ≥ 2 years), and dehydration (in 21%). Lung abscess/empyema, tracheitis, encephalopathy, bacteremia/sepsis, acute renal failure, and myocarditis were rare (each ≤ 2% of children) but associated with a median hospitalization duration of ≥ 6 days, and 48%-70% of children required intensive care. Bacterial cultures with positive results were identified in 2% of children (107/6769); Staphylococcus aureus and Streptococcus pneumoniae were most commonly identified.
  
  
  CONCLUSIONS
  Complications contribute substantially to the disease burden among children hospitalized with influenza, through intensive care requirements and prolonged hospitalization, highlighting the importance of primary prevention with influenza vaccination.
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention.
authors.forename: Fatimah S
authors.initials: FS
authors.lastname: Dawood
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Chaves
authors.forename: Alejandro
authors.initials: A
authors.lastname: Pérez
authors.forename: Arthur
authors.initials: A
authors.lastname: Reingold
authors.forename: James
authors.initials: J
authors.lastname: Meek
authors.forename: Monica M
authors.initials: MM
authors.lastname: Farley
authors.forename: Patricia
authors.initials: P
authors.lastname: Ryan
authors.forename: Ruth
authors.initials: R
authors.lastname: Lynfield
authors.forename: Craig
authors.initials: C
authors.lastname: Morin
authors.forename: Joan
authors.initials: J
authors.lastname: Baumbach
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Bennett
authors.forename: Shelley
authors.initials: S
authors.lastname: Zansky
authors.forename: Ann
authors.initials: A
authors.lastname: Thomas
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Lindegren
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.forename: Lyn
authors.initials: L
authors.lastname: Finelli
mesh_terms: D001424:Bacterial Infections / Q000209:etiology* / Q000821:virology; D002648:Child; D002675:Child, Preschool; D060085:Coinfection / Q000209:etiology* / Q000382:microbiology / Q000821:virology; D006760:Hospitalization; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000150:complications* / Q000453:epidemiology* / Q000382:microbiology / Q000821:virology; D038801:International Classification of Diseases; D058873:Pandemics; D011159:Population Surveillance; D012140:Respiratory Tract Diseases / Q000209:etiology* / Q000382:microbiology / Q000821:virology; D012621:Seasons
keywords: bacterial infection; children; children, hospitalized; complications; influenza