Three phenotypes of obstructive lung disease in the elderly

Abstract

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.