title: [Critically ill patients with 2009 pandemic influenza A (H1N1) infection in Spain: factors associated with death, April 2009-January 2010].
abstract: BACKGROUND
  It is necessary to analyse the severe cases of pandemic influenza infection in order to identify vulnerable populations and adapt prevention and control policies accordingly. We analysed the clinical and epidemiological characteristics and risk factors associated with death in patients with 2009 pandemic influenza A (H1N1) infection hospitalised in intensive care units (ICUs) in Spain and reported from 24 April 2009 to 31 January 2010.
  
  
  METHODS
  As part of the national strategy for surveillance of hospitalized cases with pandemic influenza, cased-based clinical and epidemiological information on all cases admitted to an ICU with 2009 pandemic virus (H1N1) infection was collected nationwide.
  
  
  RESULTS
  Of 1,231 cases admitted to ICU, 271 died (case fatality ratio, 22%). The median age was 40 years (range: 0-90). A total of 838 (76.3%) patients had an underlying risk condition, being respiratory disease the most frequently reported (34.1%), followed by morbid obesity (18.8%), in adults. Antiviral treatment was given in 93.1% patients and in 25.6% (n = 231) it was initiated within 48 hours of symptoms onset. In a multivariate analysis, cancer (OR 2.71, 95%CI 1.44 to 5.1), immunodeficiency (OR 2.25, 95%CI 1.29 - 3.92) and morbid obesity (OR 1.79, 95%CI 1.13 to 2.85) were significantly associated with death in adults.
  
  
  CONCLUSIONS
  The characterization of severe pandemic influenza cases has been crucial in identifying as risk factors of complications and death from influenza the presence of cancer and immunodeficiencies and for the first time, morbid obesity in adults.
authors.affiliation: Centro de Coordinación de Alertas y Emergencias Sanitarias (CCAES), Dirección General de Salud Pública y Sanidad Exterior, Ministerio de Sanidad y Política Social de España, Madrid, Spain. psantaolalla@msps.es
authors.forename: Patricia
authors.initials: P
authors.lastname: Santa-Olalla Peralta
authors.forename: Marta
authors.initials: M
authors.lastname: Cortes García
authors.forename: Aurora
authors.initials: A
authors.lastname: Limia Sánchez
authors.forename: Josefa
authors.initials: J
authors.lastname: Andrés Prado
authors.forename: Isabel
authors.initials: I
authors.lastname: Pachón Del Amo
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Sierra Moros
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death; D002648:Child; D002675:Child, Preschool; D016638:Critical Illness; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D011996:Records; D013030:Spain / Q000453:epidemiology; D013997:Time Factors; D055815:Young Adult