Lung

, Volume 191, Issue 1, pp 87–93 | Cite as

Identification of Subtypes of Refractory Asthma in Korean Patients by Cluster Analysis

  • An Soo Jang
  • Hyouk-Soo Kwon
  • You Sook Cho
  • Yun Jeong Bae
  • Tae Bum Kim
  • Jong Sook Park
  • Sung Woo Park
  • Soo-Taek Uh
  • Jae-Sung Choi
  • Yong-Hoon Kim
  • Hyeon-Kyu Hwang
  • Hee-Bom Moon
  • Choon Sik Park
Article

Abstract

Background

Refractory asthma, a subtype of asthma with uncontrolled symptoms despite antiasthma medications, is a heterogeneous syndrome with variable clinical features, presumably different etiologies, and pathophysiological mechanisms. The heterogeneity of refractory asthma, however, is poorly understood. We aimed to characterize refractory asthma and to improve our understanding of the heterogeneity of refractory asthma patients.

Methods

We identified refractory asthma patients (n = 96) as defined by the American Thoracic Society’s criteria from a cohort of Korean asthma patients (n = 2,187). Then, cluster analysis was conducted to classify subtypes of refractory asthma.

Results

Among the study group, 4.4 % (n = 96) of all asthma patients had refractory asthma. Cluster analysis identified four distinct groups of refractory asthma. Age at onset was younger in clusters 1 and 2 than in clusters 3 and 4. Patients in cluster 1 had the most well-preserved pulmonary function; patients in cluster 2 had a female predominance and the most severe airway obstruction; patients in cluster 3 were mostly female and had the most enhanced bronchial hyperresponsiveness; and patients in cluster 4 were most male and tended to be cigarette smokers.

Conclusions

The current results suggest that refractory asthma is a heterogeneous syndrome and could be classified into four subtypes. Underlying pathogenesis and therapeutic approaches may differ for the different subtypes and further research is needed.

Keywords

Asthma Cluster analysis Airway obstruction Bronchial hyperreactivity 

Abbreviations

ATS

American Thoracic Society

BHR

Bronchial hyperresponsiveness

BMI

Body mass index

COPD

Chronic obstructive pulmonary disease

ENFUMOSA

European Network for Understanding Mechanism of Severe Asthma

FEV1

Forced expiratory volume in 1 s

FVC

Forced vital capacity

GINA

Global Initiative for Asthma

ICS

Inhaled corticosteroid

LABA

Long-acting beta-agonist

PC20 M

Methacholine concentration that induced a 20 % decline of FEV1 from baseline FEV1

QOL

Quality of life

SARP

Severe Asthma Research Program

TENOR

The Epidemiology and Natural history of asthma: Outcomes and treatment Regimens

Notes

Acknowledgments

This study was supported by grants from the Korea Health 21 R&D Project, Ministry of Health, Welfare and Family Affairs (A090548 and A040153), Republic of Korea, to CSP, HBM, and YSC.

Conflict of interest

The authors have no conflicts of interest to disclose.

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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • An Soo Jang
    • 1
  • Hyouk-Soo Kwon
    • 2
  • You Sook Cho
    • 2
  • Yun Jeong Bae
    • 2
  • Tae Bum Kim
    • 2
  • Jong Sook Park
    • 1
  • Sung Woo Park
    • 1
  • Soo-Taek Uh
    • 3
  • Jae-Sung Choi
    • 4
  • Yong-Hoon Kim
    • 4
  • Hyeon-Kyu Hwang
    • 5
  • Hee-Bom Moon
    • 2
  • Choon Sik Park
    • 1
  1. 1.Division of Allergy and Respiratory Medicine, Genome Research Center for Allergy and Respiratory DiseasesSoonchunhyang University Bucheon HospitalGyeonggi-doRepublic of Korea
  2. 2.Department of Allergy and Clinical Immunology, Asan Medical CenterUniversity of Ulsan, College of MedicineSeoulRepublic of Korea
  3. 3.Division of Allergy and Respiratory MedicineSoonchunhyang University Seoul HospitalSeoulRepublic of Korea
  4. 4.Division of Allergy and Respiratory DiseaseSoonchunhyang University Cheonan HospitalCheonanRepublic of Korea
  5. 5.Division of Allergy and Respiratory DiseaseSoonchunhyang University Gumi HospitalGyeongsangbuk-doRepublic of Korea

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