title: Risk factors of A/H1N1 etiology in pneumonia and its impact on mortality.
abstract: OBJECTIVE
  Pandemic flu has changed the epidemiology of pneumonia, thus challenging the prediction of etiology and outcome. We analyze the risk factors to predict influenza A/H1N1 infection in patients with pneumonia, and the impact of this etiology on mortality during a pandemic period. Differences between pneumonia with or without A/H1N1 coinfection are described.
  
  
  METHODS
  Retrospective observational study in 364 consecutive patients hospitalized with pneumonia during the A/H1N1 pandemic flu, April-December 2009.
  
  
  RESULTS
  294 patients (80.5%) had A/H1N1(-) pneumonia, 47 (13.2%) A/H1N1(+) pneumonia, and 23 (6.3%) coinfection. Mortality during hospitalization was 24/294 (8.2%), 8/47 (16.7%), 2/23 (8.7%) respectively. A regression logistic analysis (Area under curve, AUC 0.81) to predict A/H1N1(+) pneumonia identified four independent variables: age < 60 years (Odds ratio, OR 5.9), multilobar infiltrates (OR 7.7), C-reactive protein (CRP) < 10 mg/dL (OR 2.8), and leukopenia < 5000/mm(3) (OR 3.4). Risk factors for in-hospital mortality in the whole group were A/H1N1 (+) etiology and LDH > 600 IU/L (OR 4.1) when adjusting for PSI, and hypoxemia (OR 4.2) when adjusting for CURB 65 (AUC 0.81). Heart disease (OR 27.4) and LDH > 600 IU/L (OR 10.5) were risk factors for in-hospital mortality in A/H1N1(+) patients (AUC 0.81)
  
  
  CONCLUSIONS
  Leukopenia, multilobar infiltrates, CRP<10 mg/dl and age < 60 years were independently associated with A/H1N1(+) etiology. Pandemic A/H1N1(+) increased mortality pneumonia. Heart disease and LDH > 600 were independently associated with mortality in A/H1N1(+) pneumonia.
authors.affiliation: Service of Pneumology, Hospital Universitario y Politécnico La Fe, Valencia, Spain. reyes@comv.es
authors.forename: S
authors.initials: S
authors.lastname: Reyes
authors.forename: B
authors.initials: B
authors.lastname: Montull
authors.forename: R
authors.initials: R
authors.lastname: Martínez
authors.forename: J
authors.initials: J
authors.lastname: Córdoba
authors.forename: J M
authors.initials: JM
authors.lastname: Molina
authors.forename: V
authors.initials: V
authors.lastname: Martí
authors.forename: A
authors.initials: A
authors.lastname: Martínez
authors.forename: P
authors.initials: P
authors.lastname: Ramírez
authors.forename: R
authors.initials: R
authors.lastname: Menéndez
mesh_terms: D000328:Adult; D000368:Aged; D002097:C-Reactive Protein; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000401:mortality* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D058873:Pandemics; D011024:Pneumonia, Viral / Q000150:complications / Q000401:mortality* / Q000821:virology; D012189:Retrospective Studies; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology
chemical_list: D002097:C-Reactive Protein