title: Pandemic and post-pandemic influenza A (H1N1) infection in critically ill patients.
abstract: BACKGROUND
  There is a vast amount of information published regarding the impact of 2009 pandemic Influenza A (pH1N1) virus infection. However, a comparison of risk factors and outcome during the 2010-2011 post-pandemic period has not been described.
  
  
  METHODS
  A prospective, observational, multi-center study was carried out to evaluate the clinical characteristics and demographics of patients with positive RT-PCR for H1N1 admitted to 148 Spanish intensive care units (ICUs). Data were obtained from the 2009 pandemic and compared to the 2010-2011 post-pandemic period.
  
  
  RESULTS
  Nine hundred and ninety-seven patients with confirmed An/H1N1 infection were included. Six hundred and forty-eight patients affected by 2009 (pH1N1) virus infection and 349 patients affected by the post-pandemic Influenza (H1N1)v infection period were analyzed. Patients during the post-pandemic period were older, had more chronic comorbid conditions and presented with higher severity scores (Acute Physiology And Chronic Health Evaluation II (APACHE II) and Sequential Organ Failure Assessment (SOFA)) on ICU admission. Patients from the post-pandemic Influenza (H1N1)v infection period received empiric antiviral treatment less frequently and with delayed administration. Mortality was significantly higher in the post-pandemic period. Multivariate analysis confirmed that haematological disease, invasive mechanical ventilation and continuous renal replacement therapy were factors independently associated with worse outcome in the two periods. HIV was the only new variable independently associated with higher ICU mortality during the post-pandemic Influenza (H1N1)v infection period.
  
  
  CONCLUSIONS
  Patients from the post-pandemic Influenza (H1N1)v infection period had an unexpectedly higher mortality rate and showed a trend towards affecting a more vulnerable population, in keeping with more typical seasonal viral infection.
authors: Critical Care Center, Parc Taulí Hospital-Sabadell, CIBERes, Sabadell, Spain. drmartinloeches@gmail.com
authors: Ignacio
authors: I
authors: Martin-Loeches
authors: Emili
authors: E
authors: Díaz
authors: Loreto
authors: L
authors: Vidaur
authors: Antoni
authors: A
authors: Torres
authors: Cesar
authors: C
authors: Laborda
authors: Rosa
authors: R
authors: Granada
authors: Juan
authors: J
authors: Bonastre
authors: Mar
authors: M
authors: Martín
authors: Josu
authors: J
authors: Insausti
authors: Angel
authors: A
authors: Arenzana
authors: Jose Eugenio
authors: JE
authors: Guerrero
authors: Ines
authors: I
authors: Navarrete
authors: Jesus
authors: J
authors: Bermejo-Martin
authors: David
authors: D
authors: Suarez
authors: Alejandro
authors: A
authors: Rodriguez
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D016638:Critical Illness / Q000453:epidemiology* / Q000401:mortality; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D007362:Intensive Care Units / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D058873:Pandemics / Q000706:statistics & numerical data*; D011446:Prospective Studies; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D018709:Statistics, Nonparametric; D055815:Young Adult