Study of the clinical phenotype of symptomatic chronic airways disease by hierarchical cluster analysis and two-step cluster analyses / 中华内科杂志

ABSTRACT

Objective To study the distinct clinical phenotype of chronic airway diseases by hierarchical cluster analysis and two-step cluster analysis.Methods A population sample of adult patients in Donghuamen community,Dongcheng district and Qinghe community,Haidian district,Beijing from April 2012 to January 2015,who had wheeze within the last 12 months,underwent detailed investigation,including a clinical questionnaire,pulmonary function tests,total serum IgE levels,blood eosinophil level and a peak flow diary.Nine variables were chosen as evaluating parameters,including pre-salbutamol forced expired volume in one second(FEV1)/forced vital capacity (FVC) ratio,pre-salbutamol FEV1,percentage of post-salbutamol change in FEV1,residual capacity,diffusing capacity of the lung for carbon monoxide/alveolar volume adjusted for haemoglobin level,peak expiratory flow (PEF) variability,serum IgE level,cumulative tobacco cigarette consumption (pack-years) and respiratory symptoms (cough and expectoration).Subjects' different clinical phenotype by hierarchical cluster analysis and two-step cluster analysis was identified.Results (1) Four clusters were identified by hierarchical cluster analysis.Cluster 1 was chronic bronchitis in smokers with normal pulmonary function.Cluster 2 was chronic bronchitis or mild chronic obstructive pulmonary disease (COPD) patients with mild airflow limitation.Cluster 3 included COPD patients with heavy smoking,poor quality of life and severe airflow limitation.Cluster 4 recognized atopic patients with mild airflow limitation,elevated serum IgE and clinical features of asthma.Significant differences were revealed regarding pre-salbutamol FEV1/FVC％,pre-salbutamol FEV1％ pred,postsalbutamol change in FEV1 ％,maximal mid-expiratory flow curve (MMEF)％ pred,carbon monoxide diffusing capacity per liter of alveolar(DLCO)/(VA)％ pred,residual volume(RV)％ pred,total serum IgE level,smoking history (pack-years),St.George' s respiratory questionnaire (SGRQ) score,acute exacerbation in the past one year,PEF variability and allergic dermatitis (P ＜ 0.05).(2) Four clusters were also identified by two-step cluster analysis as followings,cluster 1,COPD patients with moderate to severe airflow limitation;cluster 2,asthma and COPD patients with heavy smoking,airflow limitation and increased airways reversibility;cluster 3,patients having less smoking and normal pulmonary function with wheezing but no chronic cough;cluster 4,chronic bronchitis patients with normal pulmonary function and chronic cough.Significant differences were revealed regarding gender distribution,respiratory symptoms,pre-salbutamol FEV1/FVC％,pre-salbutamol FEV1 ％ pred,post-salbutamol change in FEV1 ％,MMEF％ pred,DLCO/VA％ pred,RV％ pred,PEF variability,total serum IgE level,cumulative tobacco cigarette consumption (pack-years),and SGRQ score (P ＜ 0.05).Conclusion By different cluster analyses,distinct clinical phenotypes of chronic airway diseases are identified.Thus,individualized treatments may guide doctors to provide based on different phenotypes.