title: Identification and characterization of near-fatal asthma phenotypes by cluster analysis.
abstract: BACKGROUND
  Near-fatal asthma (NFA) is a heterogeneous clinical entity and several profiles of patients have been described according to different clinical, pathophysiological and histological features. However, there are no previous studies that identify in a unbiased way--using statistical methods such as clusters analysis--different phenotypes of NFA. Therefore, the aim of the present study was to identify and to characterize phenotypes of near fatal asthma using a cluster analysis.
  
  
  METHODS
  Over a period of 2 years, 33 Spanish hospitals enrolled 179 asthmatics admitted for an episode of NFA. A cluster analysis using two-steps algorithm was performed from data of 84 of these cases.
  
  
  RESULTS
  The analysis defined three clusters of patients with NFA: cluster 1, the largest, including older patients with clinical and therapeutic criteria of severe asthma; cluster 2, with an high proportion of respiratory arrest (68%), impaired consciousness level (82%) and mechanical ventilation (93%); and cluster 3, which included younger patients, characterized by an insufficient anti-inflammatory treatment and frequent sensitization to Alternaria alternata and soybean.
  
  
  CONCLUSIONS
  These results identify specific asthma phenotypes involved in NFA, confirming in part previous findings observed in studies with a clinical approach. The identification of patients with a specific NFA phenotype could suggest interventions to prevent future severe asthma exacerbations.
authors.affiliation: Pneumology Department, Hospital Comarcal d'Inca, Balearic Islands, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Serrano-Pariente
authors.affiliation: Emergency Department, Hospital Central de las Fuerzas Armadas, Montevideo, Uruguay.
authors.forename: G
authors.initials: G
authors.lastname: Rodrigo
authors.affiliation: Pneumology Department, Hospital Germans Trias i Pujol de Badalona (Barcelona), Institut de Bioingenieria de Catalunya (IBEC), Barcelona, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Fiz
authors.affiliation: Pneumology Department, Hospital de la Santa Creu i de Sant Pau de Barcelona, Institut d'Investigació Biomédica Sant Pau (IIB Sant Pau), Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Crespo
authors.affiliation: Pneumology Department, Hospital de la Santa Creu i de Sant Pau de Barcelona, Institut d'Investigació Biomédica Sant Pau (IIB Sant Pau), Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Plaza
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology* / Q000628:therapy; D016000:Cluster Analysis; D015897:Comorbidity; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012307:Risk Factors; D012720:Severity of Illness Index; D013030:Spain / Q000453:epidemiology
keywords: asthma; cluster analysis; mechanical ventilation; near-fatal asthma; phenotypes