title: Distinguishing characteristics between pandemic 2009-2010 influenza A (H1N1) and other viruses in patients hospitalized with respiratory illness.
abstract: BACKGROUND
  Differences in clinical presentation and outcomes among patients infected with pandemic 2009 influenza A H1N1 (pH1N1) compared to other respiratory viruses have not been fully elucidated.
  
  
  RESULTS
  A retrospective study was performed of all hospitalized patients at the peak of the pH1N1 season in whom a single respiratory virus was detected by a molecular assay targeting 18 viruses/subtypes (RVP, Luminex xTAG). Fifty-two percent (615/1192) of patients from October, 2009 to December, 2009 had a single respiratory virus (291 pH1N1; 207 rhinovirus; 45 RSV A/B; 37 parainfluenza; 27 adenovirus; 6 coronavirus; and 2 metapneumovirus). No seasonal influenza A or B was detected. Individuals with pH1N1, compared to other viruses, were more likely to present with fever (92% & 70%), cough (92% & 86%), sore throat (32% & 16%), nausea (31% & 8%), vomiting (39% & 30%), abdominal pain (14% & 7%), and a lower white blood count (8,500/L & 13,600/L, all p-values<0.05). In patients with cough and gastrointestinal complaints, the presence of subjective fever/chills independently raised the likelihood of pH1N1 (OR 10). Fifty-five percent (336/615) of our cohort received antibacterial agents, 63% (385/615) received oseltamivir, and 41% (252/615) received steroids. The mortality rate of our cohort was 1% (7/615) and was higher in individuals with pH1N1 compared to other viruses (2.1% & 0.3%, respectively; p = 0.04).
  
  
  CONCLUSIONS
  During the peak pandemic 2009-2010 influenza season in Rhode Island, nearly half of patients admitted with influenza-like symptoms had respiratory viruses other than influenza A. A high proportion of patients were treated with antibiotics and pH1N1 infection had higher mortality compared to other respiratory viruses.
authors.affiliation: Division of Infectious Diseases, Rhode Island Hospital, Providence, Rhode Island, United States of America.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Chan
authors.forename: Leonard A
authors.initials: LA
authors.lastname: Mermel
authors.forename: Sarah B
authors.initials: SB
authors.lastname: Andrea
authors.forename: Russell
authors.initials: R
authors.lastname: McCulloh
authors.forename: John P
authors.initials: JP
authors.lastname: Mills
authors.forename: Ignacio
authors.initials: I
authors.lastname: Echenique
authors.forename: Emily
authors.initials: E
authors.lastname: Leveen
authors.forename: Natasha
authors.initials: N
authors.lastname: Rybak
authors.forename: Cheston
authors.initials: C
authors.lastname: Cunha
authors.forename: Jason T
authors.initials: JT
authors.lastname: Machan
authors.forename: Terrance T
authors.initials: TT
authors.lastname: Healey
authors.forename: Kimberle C
authors.initials: KC
authors.lastname: Chapin
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003710:Demography; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000502:physiology*; D007251:Influenza, Human / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000821:virology*; D016015:Logistic Models; D008297:Male; D058873:Pandemics / Q000706:statistics & numerical data*; D013902:Radiography, Thoracic; D012237:Rhode Island / Q000453:epidemiology; D016896:Treatment Outcome