title: Severe or life-threatening asthma exacerbation: patient heterogeneity identified by cluster analysis.
abstract: Severe or life-threatening asthma exacerbation is one of the worst outcomes of asthma because of the risk of death. To date, few studies have explored the potential heterogeneity of this condition.
  
  
  
  To examine the clinical characteristics and heterogeneity of patients with severe or life-threatening asthma exacerbation.
  
  
  
  This was a multicentre, prospective study of patients with severe or life-threatening asthma exacerbation and pulse oxygen saturation < 90% who were admitted to 17 institutions across Japan. Cluster analysis was performed using variables from patient- and physician-orientated structured questionnaires.
  
  
  
  Analysis of data from 175 patients with severe or life-threatening asthma exacerbation revealed five distinct clusters. Cluster 1 (n = 27) was younger-onset asthma with severe symptoms at baseline, including limitation of activities, a higher frequency of treatment with oral corticosteroids and short-acting beta-agonists, and a higher frequency of asthma hospitalizations in the past year. Cluster 2 (n = 35) was predominantly composed of elderly females, with the highest frequency of comorbid, chronic hyperplastic rhinosinusitis/nasal polyposis, and a long disease duration. Cluster 3 (n = 40) was allergic asthma without inhaled corticosteroid use at baseline. Patients in this cluster had a higher frequency of atopy, including allergic rhinitis and furred pet hypersensitivity, and a better prognosis during hospitalization compared with the other clusters. Cluster 4 (n = 34) was characterized by elderly males with concomitant chronic obstructive pulmonary disease (COPD). Although cluster 5 (n = 39) had very mild symptoms at baseline according to the patient questionnaires, 41% had previously been hospitalized for asthma.
  
  
  
  This study demonstrated that significant heterogeneity exists among patients with severe or life-threatening asthma exacerbation. Differences were observed in the severity of asthma symptoms and use of inhaled corticosteroids at baseline, and the presence of comorbid COPD. These findings may contribute to a deeper understanding and better management of this patient population.
authors.affiliation: Clinical Research Center for Allergology and Rheumatology, Sagamihara National Hospital, Sagamihara, Japan.|Department of Respiratory Medicine, Toho University Omori Medical Center, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sekiya
authors.affiliation: Translational Research Informatics Center, Foundation for Biomedical Research and Innovation, Kobe, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Nakatani
authors.affiliation: Clinical Research Center for Allergology and Rheumatology, Sagamihara National Hospital, Sagamihara, Japan.
authors.forename: Y
authors.identifier: 0000-0001-9913-4524
authors.initials: Y
authors.lastname: Fukutomi
authors.affiliation: Translational Research Informatics Center, Foundation for Biomedical Research and Innovation, Kobe, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kaneda
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Iikura
authors.affiliation: Department of Internal Medicine, National Hospital Organization Fukuoka Hospital, Fukuoka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Respiratory Diseases and Chest Surgery, Otsu Red Cross Hospital, Otsu, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Respiratory Medicine, Kobe City Medical Center General Hospital, Kobe, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tomii
authors.affiliation: Department of Respiratory Medicine, Fujisawa City Hospital, Fujisawa, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nishikawa
authors.affiliation: Department of Pulmonary Medicine, Kameda Medical Center, Kamogawa, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kaneko
authors.affiliation: Department of Respiratory Medicine, Toyota Memorial Hospital, Toyota, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Sugino
authors.affiliation: Respiratory Disease Center, Yokohama City University Medical Center, Yokohama, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Shinkai
authors.affiliation: The Department of Respiratory Medicine, Saiseikai Nakatsu Hospital, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ueda
authors.affiliation: Department of Respiratory Medicine and Clinical Immunology, Toyota Kosei Hospital, Toyota, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tanikawa
authors.affiliation: Department of Respiratory Medicine, Shizuoka General Hospital, Shizuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Shirai
authors.affiliation: Department of Respiratory Diseases, Hyogo Prefectural Amagasaki Hospital, Amagasaki, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hirabayashi
authors.affiliation: Department of Internal Medicine, Respiratory Division, Tokai University School of Medicine, Isehara, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Aoki
authors.affiliation: Department of Respiratory Medicine and Allergology, Kariya Toyota General Hospital, Kariya, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kato
authors.affiliation: Internal Medicine, Public Tomioka General Hospital, Tomioka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Iizuka
authors.affiliation: Department of Respiratory Medicine, Toho University Omori Medical Center, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Homma
authors.affiliation: Clinical Research Center for Allergology and Rheumatology, Sagamihara National Hospital, Sagamihara, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: NPO Sapporo Cough Asthma and Allergy Center, Sapporo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology* / Q000628:therapy; D016000:Cluster Analysis; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D006760:Hospitalization; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011446:Prospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
keywords: cluster analysis; exacerbation; heterogeneity; life-threatening asthma; near-fatal asthma