Objective To investigate the phenotyping of COPD by cluster analysis and evaluate the value of this method.Methods 168 COPD patients were enrolled from Beijing Tongren Hospital. Demographic and clinical data, such as, sex, age, body mass index ( BMI) , smoking index, course of disease,exacerbation rate, and comorbidities were collected. Pulmonary function test, emphysema scoring by HRCT,dyspnea by MMRC score, COPD assessment test ( CAT) score, six-minute walk test were performed for each patient during the stable stage. Cluster analysis was conducted using SPSS 13. 0. Results According to the GOLD criteria,5, 75, 75, and 13 patients were classified into GOLD stage 1, 2, 3, and 4, respectively. There was no difference among different stages in sex distribution, BMI, smoking index, hypertension, and cerebral infarction incidence( P gt; 0. 05) , but the differences in age, disease course, dyspnea score, six-minute walk distance, BODE score, CAT score, coronary heart disease, exacerbation rate, and HRCT emphysema visual score were significant( P lt;0. 05) . By cluster analysis,168 patients were finally classified into three groups:younger/mild, older/ severe, and older/moderate. The patients with the same GOLD stage appeared indifferent clusters and the patients belonging to different GOLD stages could be in the same cluster. There were significant differences among three groups in age, BMI, exacerbation rate, dyspnea score, CAT score, and comorbidities. The result showed that HRCT emphysema visual score was also an important index todifferentiate clusters, suggesting that emphysema was an important phenotype of COPD. Conclusions Cluster analysis can classify homogeneous subjects into the same cluster, and heterogeneous subjects into different clusters. The results suggest that COPD phenotyping by cluster analysis is clinically useful and significant.
Chronic obstructive pulmonary disease (COPD) is one of the common chronic airway disorders, which accounts for the third to fourth cause of death worldwide. Recently, the focuses of researches are on the multi-factorial risks for development of COPD, mechanisms related to COPD development, early detection and early intervention of COPD, individualized use of long-term maintenance medications as well as phenotypes of acute exacerbation of COPD and their corresponding management. There are huge amount of COPD patients with variety of risk factors or different phenotypes in China, which makes it possible to establish a network for cohort study or real life registration study of COPD. The results will provide new information on the characteristics of COPD in China. Individualized treatment could be recommended according to the phenotypes or endotypes information. All these new findings or progresses could provide impetus for improvement of the ability of research and clinical management of COPD to the worldwide top level.