Three phenotypes of obstructive lung disease in the elderly

SETTING: Eleven referring hospitals in South Korea. OBJECTIVE: To classify the phenotypes in elderly subjects with obstructive lung disease (OLD). METHODS: We analysed 191 subjects aged >= 60 years with chronic respiratory symptoms and either obstructive spirometry or bronchial hyperresponsiveness. Factor analysis was performed using commonly measured variables and revealed four significant variables: 1) the ratio of inspiratory capacity to total lung capacity, 2) the total score on the St George's Respiratory Questionnaire, 3) the volume fraction of the lung less than 950 Hounsfield Unit at full inspiration on volumetric computed tomography and 4) post-bronchodilator forced expiratory volume in 1 second (FEV(1)) changes. We performed a cluster analysis on these four variables. RESULTS: The mean age was 68.5 (+/- 5.2 SD) years and the mean post-bronchodilator FEV(1) was 52.4% (+/- 16.5) predicted. Three clusters with the following phenotypes were identified: Cluster 1 included subjects with moderate to severe airflow obstruction and bronchodilator reversibility; Cluster 2 subjects had moderate airflow obstruction without bronchodilator reversibility, and Cluster 3 subjects had severe airflow obstruction without bronchodilator reversibility. CONCLUSIONS: We identified three phenotypes in elderly subjects with OLD. Follow-up studies are needed to explore the clinical significance of each phenotype.This study was supported by grants from the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare and Family Affairs, Republic of Korea (A040153) and the Asan Institute for Life Science, Seoul, Korea (05-306).; JBS has been an investigator in a government-sponsored study (2006-2008 Korea Science and Engineering Foundation). YMO has been an investigator in university-sponsored studies (University of Ulsan College of Medicine) and an industry-sponsored study (AstraZeneca Korea, and MSD Korea), and has been an invited speaker at scientific meetings organised and financed by various pharmaceutical companies (GlaxoSmithKline, AstraZeneca Korea, MSD Korea, and Boehringer Ingelheim). SDL serves as a consultant to GlaxoSmithKline, and has been an invited speaker at scientific meetings organised and financed by various pharmaceutical companies (GlaxoSmithKline, AstraZeneca Korea, and Boehringer Ingelheim). The remaining authors have no conflicts of interest to disclose