Identification of subtypes in subjects with mild-to-moderate airflow limitation and its clinical and socioeconomic implications

Jin Hwa Lee, Chin Kook Rhee, Kyungjoo Kim, Jee Ae Kim, Sang Hyun Kim, Kwang Ha Yoo, Woo Jin Kim, Yong Bum Park, Hye Yun Park, Ki Suck Jung

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10 Scopus citations


Purpose: The purpose of this study was to identify subtypes in patients with mild-to-moderate airflow limitation and to appreciate their clinical and socioeconomic implications. Methods: Subjects who were aged ≥20 years and had forced expiratory volume in 1 second (FEV1) ≥60% predicted and FEV1/forced vital capacity <0.7 were selected from the fourth Korea National Health and Nutrition Examination Survey (KNHANES) in 2007–2012. The data were merged to the National Health Insurance reimbursement database during the same period. k-Means clustering was performed to explore subtypes. For clustering analysis, six key input variables – age, body mass index (BMI), FEV1% predicted, the presence or absence of self-reported wheezing, smoking status, and pack-years of smoking – were selected. Results: Among a total of 2,140 subjects, five groups were identified through k-means clustering, namely putative “near-normal (n=232),” “asthmatic (n=392),” “chronic obstructive pulmonary disease (COPD) (n=37),” “asthmatic-overlap (n=893),” and “COPD-overlap (n=586)” subtypes. Near-normal group showed the oldest mean age (72±7 years) and highest FEV1 (102%±8% predicted), and asthmatic group was the youngest (46±9 years). COPD and COPD-overlap groups were male predominant and all current or ex-smokers. While asthmatic group had the lowest prescription rate despite the highest proportion of self-reported wheezing, COPD, asthmatic-overlap, and COPD-overlap groups showed high prescription rate of respiratory medicine. Although COPD group formed only 1.7% of total subjects, they showed the highest mean medical cost and health care utilization, comprising 5.3% of the total medical cost. When calculating a ratio of total medical expense to household income, the mean ratio was highest in the COPD group. Conclusion: Clinical and epidemiological heterogeneities of subjects with mild-to-moderate airflow limitation and a different level of health care utilization by each subtype are shown. Identification of a subtype with high health care demand could be a priority for effective utilization of limited resources.

Original languageEnglish
Pages (from-to)1135-1144
Number of pages10
JournalInternational Journal of COPD
StatePublished - 12 Apr 2017


  • Asthma
  • COPD
  • Cluster
  • Health care utilization
  • Overlap
  • Phenotype


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