title: Hospital-onset influenza hospitalizations--United States, 2010-2011.
abstract: BACKGROUND
  Seasonal influenza is responsible for more than 200,000 hospitalizations each year in the United States. Although hospital-onset (HO) influenza contributes to morbidity and mortality among these patients, little is known about its overall epidemiology.
  
  
  OBJECTIVE
  We describe patients with HO influenza in the United States during the 2010-2011 influenza season and compare them with community-onset (CO) cases to better understand factors associated with illness.
  
  
  METHODS
  We identified laboratory-confirmed, influenza-related hospitalizations using the Influenza Hospitalization Surveillance Network (FluSurv-NET), a network that conducts population-based surveillance in 16 states. CO cases had laboratory confirmation ≤ 3 days after hospital admission; HO cases had laboratory confirmation > 3 days after admission.
  
  
  RESULTS
  We identified 172 (2.8%) HO cases among a total of 6,171 influenza-positive hospitalizations. HO and CO cases did not differ by age (P = .22), sex (P = .29), or race (P = .25). Chronic medical conditions were more common in HO cases (89%) compared with CO cases (78%) (P < .01), and a greater proportion of HO cases (42%) than CO cases (17%) were admitted to the intensive care unit (P < .01). The median length of stay after influenza diagnosis of HO cases (7.5 days) was greater than that of CO cases (3 days) (P < .01).
  
  
  CONCLUSIONS
  HO cases had greater length of stay and were more likely to be admitted to the intensive care unit or die compared with CO cases. HO influenza may play a role in the clinical outcome of hospitalized patients, particularly among those with chronic medical conditions.
authors.affiliation: Epidemiology and Prevention Branch, Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA. Electronic address: MJhung@cdc.gov.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Jhung
authors.affiliation: Epidemiology and Prevention Branch, Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Tiffany
authors.initials: T
authors.lastname: D'Mello
authors.affiliation: Epidemiology and Prevention Branch, Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Pérez
authors.affiliation: Colorado Department of Public Health and Environment, Denver, CO.
authors.forename: Deborah
authors.initials: D
authors.lastname: Aragon
authors.affiliation: Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY.
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Bennett
authors.affiliation: Rhode Island Department of Health, Providence, RI.
authors.forename: Tara
authors.initials: T
authors.lastname: Cooper
authors.affiliation: Georgia Division of Public Health, Georgia Emerging Infections Program, Emory University, Atlanta, GA.
authors.forename: Monica M
authors.initials: MM
authors.lastname: Farley
authors.affiliation: Ohio Department of Health, Columbus, OH.
authors.forename: Brian
authors.initials: B
authors.lastname: Fowler
authors.affiliation: Oklahoma State Department of Health, Oklahoma City, OK.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Grube
authors.affiliation: New Mexico Department of Health, Santa Fe, NM.
authors.forename: Emily B
authors.initials: EB
authors.lastname: Hancock
authors.affiliation: Minnesota Department of Health, St Paul, MN.
authors.forename: Ruth
authors.initials: R
authors.lastname: Lynfield
authors.affiliation: Minnesota Department of Health, St Paul, MN.
authors.forename: Craig
authors.initials: C
authors.lastname: Morin
authors.affiliation: California Emerging Infections Program, Oakland, CA.
authors.forename: Arthur
authors.initials: A
authors.lastname: Reingold
authors.affiliation: Maryland Department of Health and Mental Hygiene, Baltimore, MD.
authors.forename: Patricia
authors.initials: P
authors.lastname: Ryan
authors.affiliation: Department of Preventive Medicine, Vanderbilt University School of Medicine, Nashville, TN.
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.affiliation: Michigan Department of Community Health, Lansing, MI.
authors.forename: Ruta
authors.initials: R
authors.lastname: Sharangpani
authors.affiliation: Idaho Department of Health and Welfare, Boise, ID.
authors.forename: Leslie
authors.initials: L
authors.lastname: Tengelsen
authors.affiliation: Oregon Public Health Division, Portland, OR.
authors.forename: Ann
authors.initials: A
authors.lastname: Thomas
authors.affiliation: Salt Lake Valley Health Department, Salt Lake City, UT.
authors.forename: Diana
authors.initials: D
authors.lastname: Thurston
authors.affiliation: Connecticut Emerging Infections Program, Yale School of Public Health, New Haven, CT.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Yousey-Hindes
authors.affiliation: Ohio Department of Health, Columbus, OH.
authors.forename: Shelley
authors.initials: S
authors.lastname: Zansky
authors.affiliation: Epidemiology and Prevention Branch, Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Lyn
authors.initials: L
authors.lastname: Finelli
authors.affiliation: Epidemiology and Prevention Branch, Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Chaves
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000401:mortality / Q000473:pathology; D003422:Critical Care / Q000706:statistics & numerical data; D003428:Cross Infection / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D016019:Survival Analysis; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: Health care associated