title: Predictors of pandemic (H1N1) 2009 virus positivity and adverse outcomes among hospitalized patients with a compatible syndrome.
abstract: BACKGROUND
  A pandemic (H1N1) influenza A virus was identified in 2009.
  
  
  OBJECTIVE
  To investigate predictors for pandemic (H1N1) 2009 virus infection among hospitalized patients with a flu-like illness and to identify parameters suggesting a severe clinical course.
  
  
  METHODS
  We analyzed a cohort of all patients hospitalized during a 2 month period with a flu-like syndrome who were tested for pandemic (H1N1) 2009 infection. Demographic, clinical and laboratory, along with outcome parameters, were recorded and compared between pandemic (H1N1) 2009 virus-positive and negative hospitalized patients.
  
  
  RESULTS
  Of the 179 examined hospitalized patients suspected of having pandemic (H1N1) 2009 infection 65 (36%) were found positive. These patients tended to be younger and had significantly fewer comorbidities. In addition, they had a significantly higher frequency of fever (94%), cough (86%) and myalgia (29%). Furthermore, age 65 years and cough were independent predictors for pandemic (H1N1) 2009 virus positivity in a multivariate regression analysis. Notably, 14 of the 65 positive patients (21.5%) had acute respiratory insufficiency requiring treatment in the intensive care unit. These patients were neither older nor previously sicker than patients with non-severe disease, but were distinguished by augmented inflammatory markers, significant lymphopenia associated with disease severity, and overall mortality of 21.4%.
  
  
  CONCLUSIONS
  Pandemic (H1N1) 2009 virus-positive hospitalized patients tend to be younger and have fewer comorbidities as compared to compatible negative patients. A significant number of relatively young and previously healthy positive patients might develop severe disease associated with a robust inflammatory reaction and significant lymphopenia.
authors.affiliation: Department of Medicine B, Tel Aviv Sourasky Medical Center, Israel. amirsh@tasmc.health.gov.il
authors.forename: Amir
authors.initials: A
authors.lastname: Shlomai
authors.forename: Amir
authors.initials: A
authors.lastname: Nutman
authors.forename: Taly
authors.initials: T
authors.lastname: Kotlovsky
authors.forename: Vered
authors.initials: V
authors.lastname: Schechner
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Carmeli
authors.forename: Hanan
authors.initials: H
authors.lastname: Guzner-Gur
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D007557:Israel / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D011237:Predictive Value of Tests; D011379:Prognosis; D012307:Risk Factors; D055815:Young Adult