title: Child, household, and caregiver characteristics associated with hospitalization for influenza among children 6-59 months of age: an emerging infections program study.
abstract: BACKGROUND
  Young children are at increased risk of severe outcomes from influenza illness, including hospitalization. We conducted a case-control study to identify risk factors for influenza-associated hospitalizations among children in US Emerging Infections Program sites.
  
  
  METHODS
  Cases were children 6-59 months of age hospitalized for laboratory-confirmed influenza infections during 2005-2008. Age- and zip-code-matched controls were enrolled. Data on child, caregiver and household characteristics were collected from parents and medical records. Conditional logistic regression was used to identify independent risk factors for hospitalization.
  
  
  RESULTS
  We enrolled 290 (64%) of 454 eligible cases and 1089 (49%) of 2204 eligible controls. Risk for influenza hospitalization increased with maternal age <26 years [odds ratio (OR): 1.8, 95% confidence interval (CI): 1.1-2.9]; household income below the poverty threshold (OR: 2.2, 95% CI: 1.4-3.6); smoking by >50% of household members (OR: 2.9, 95% CI: 1.4-6.6); lack of household influenza vaccination (OR: 1.8, 95% CI: 1.2-2.5) and presence of chronic illnesses, including hematologic/oncologic (OR: 11.8, 95% CI: 4.5-31.0), pulmonary (OR: 2.9, 95% CI: 1.9-4.4) and neurologic (OR: 3.8, 95% CI: 1.6-9.2) conditions. Full influenza immunization decreased the risk among children 6-23 months of age (OR: 0.5, 95% CI: 0.3-0.9) but not among those 24-59 months of age (OR: 1.5, 95% CI: 0.8-3.0; P value for difference = 0.01).
  
  
  CONCLUSIONS
  Chronic illnesses, young maternal age, poverty, household smoking and lack of household influenza vaccination increased the risk of influenza hospitalization. These characteristics may help providers to identify young children who are at greatest risk for severe outcomes from influenza illness.
authors.affiliation: From the *Influenza Division, Centers for Disease Control and Prevention; †Battelle Memorial Institute, Atlanta, GA; ‡Colorado Department of Public Health and Environment, Denver, CO; §Minnesota Department of Health, St. Paul, MN; ¶Oregon Public Health Division, Portland, OR; ‖Connecticut Emerging Infections Program, New Haven, CT; **Emory University School of Medicine and the Atlanta VA Medical Center; ††Georgia Emerging Infections Program, Atlanta, GA; ‡‡California Emerging Infections Program, Oakland, CA; §§Tennessee Department of Health; ¶¶Department of Preventive Medicine, Vanderbilt University School of Medicine, Nashville, TN; ‖‖University of Rochester School of Medicine and Dentistry, Rochester; ***New York State Department of Health, Albany, NY; †††New Mexico Department of Health, Santa Fe; and ‡‡‡University of New Mexico, Albuquerque, NM.
authors.forename: Nila J
authors.initials: NJ
authors.lastname: Dharan
authors.forename: Leslie Z
authors.initials: LZ
authors.lastname: Sokolow
authors.forename: Po-Yung
authors.initials: PY
authors.lastname: Cheng
authors.forename: Paul
authors.initials: P
authors.lastname: Gargiullo
authors.forename: Ken
authors.initials: K
authors.lastname: Gershman
authors.forename: Ruth
authors.initials: R
authors.lastname: Lynfield
authors.forename: Craig
authors.initials: C
authors.lastname: Morin
authors.forename: Ann
authors.initials: A
authors.lastname: Thomas
authors.forename: James
authors.initials: J
authors.lastname: Meek
authors.forename: Monica M
authors.initials: MM
authors.lastname: Farley
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Arnold
authors.forename: Arthur
authors.initials: A
authors.lastname: Reingold
authors.forename: Allen S
authors.initials: AS
authors.lastname: Craig
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Bennett
authors.forename: Shelley
authors.initials: S
authors.lastname: Zansky
authors.forename: Joan
authors.initials: J
authors.lastname: Baumbach
authors.forename: Sarah
authors.initials: S
authors.lastname: Lathrop
authors.forename: Laurie
authors.initials: L
authors.lastname: Kamimoto
authors.forename: David K
authors.initials: DK
authors.lastname: Shay
mesh_terms: D000293:Adolescent; D000328:Adult; D017028:Caregivers / Q000706:statistics & numerical data*; D016022:Case-Control Studies; D002675:Child, Preschool; D021821:Communicable Diseases, Emerging / Q000453:epidemiology* / Q000628:therapy* / Q000821:virology; D005191:Family Characteristics; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000453:epidemiology* / Q000628:therapy*; D008297:Male; D009035:Mothers; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult