Investigation of distinct clinical phenotypes of airways disease in the elderly based on hierarchical cluster analysis

ABSTRACT

Objective To explore the clinical phenotype of airways disease in elderly patients using hierarchical cluster analysis.Methods A total of 67 elderly patients with respiratory symptoms were enrolled in a prospective study.Demographic and clinical data,such as respiratory symptoms,cumulative tobacco cigarette consumption,acute exacerbation,atopic symptoms and peak flow diary were collected.Pulmonary function tests,blood tests (total serum IgE level and blood eosinophil level) were performed in each patient during the stable stage.Then patients with different clinical phenotype were identified by hierarchical cluster analysis.Results Four clusters were identified with the following characteristics by hierarchical cluster

analysis:

cluster 1,atopic patients with no smoking,normal lung function,but increased total serum IgE levels and asthma symptom;cluster 2,patients with no smoking and normal pulmonary function with wheezing but without chronic cough;cluster 3,patients with chronic obstructive pulmonary disease and smoking,severe airflow limitation and poor quality of life;cluster 4,patients with asthma-chronic obstructive pulmonary disease overlap syndrome and smoking,airflow limitation and increased total serum IgE levels.The forced expiratory volume in 1 second (FEV1) / forced vital capacity (FVC) ratio,FEV1/predicted value,rate of FEV1 change,maximal mid-expiratory flow (MMEF)/ predicted value,the diffusion lung capacity for carbon monoxide (DLCO)/alveolar volume (VA)/predicted value,residual volume (RV)/ predicted value,total serum Ig E levels,cumulative tobacco cigarette consumption,the St.George's Respiratory Questionnaire (SGRQ) score had significant differences in patients before versus after treatment (all P＜0.05 or P＜0.01).Conclusions Based on hierarchical cluster analysis,distinct clinical phenotypes of airways disease in elderly patients can be identified.Conclusions With patients having asthma or COPD alone,patients with Asthma-COPD overlap syndrome (ACOS) always experience a more rapid decline in lung function and frequent exacerbations,having poor health-related quality-of-life (HRQOL) outcomes,which deserve our high attention.