Abstract
Background This study aimed to evaluate the efficacy of the emphysema index (EI) in distinguishing chronic bronchitis (CB) from chronic obstructive pulmonary disease (COPD) and its role, combined with the COPD Assessment Test (CAT) score, in the evaluation of COPD. Methods A total of 92 patients with CB and 277 patients with COPD were enrolled in this study. Receiver operating characteristic (ROC) curves were analyzed to evaluate whether the EI can preliminarily distinguish chronic bronchitis from COPD. Considering the heterogeneity of COPD, there might be missed diagnosis of some patients with bronchitis type when differentiating COPD patients only by EI. Therefore, patients with COPD were classified according to the CAT score and EI into four groups: Group 1 (EI < 16%, CAT < 10), Group 2 (EI < 16%, CAT ≥ 10), Group 3 (EI ≥ 16%, CAT < 10), and Group 4 (EI ≥ 16%, CAT ≥ 10). The records of pulmonary function and quantitative computed tomography findings were retrospectively analyzed. Results ROC curve analysis showed that EI = 16.2% was the cutoff value for distinguishing COPD from CB. Groups 1 and 2 exhibited significantly higher maximal voluntary ventilation (MVV) percent predicted (pred), forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC), maximal midexpiratory flow of 25–75% pred, carbon monoxide-diffusing capacity (DLCO)/alveolar ventilation (VA), FEV1 % pred (p ≤ 0.013), and maximal expiratory flow 50% pred (all p < 0.05) than Group 4. FEV1/FVC and DLCO/VA were significantly lower in Group 3 than in Group 2 (p=0.002 and p < 0.001, respectively). The residual volume/total lung capacity was higher in Group 3 than in Groups 1 and 2 (p < 0.05). Conclusions The combination of EI and CAT was effective in the evaluation of COPD.
Highlights
Chronic obstructive pulmonary disease (COPD), a heterogeneous chronic inflammatory airway condition, is one of the leading causes of death with increasing morbidity and mortality worldwide [1, 2]. e definition of COPD is given as a common, preventable, and treatable disease that is characterized by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities, usually caused by significant exposure to noxious particles or gases [3]. e diagnosis and assessment of COPD were mainly based on the pulmonary function according to the Global Initiative for Chronic Obstructive Lung Disease guidelines [4]
A COPD Assessment Test (CAT) score ≥10 is recommended as the threshold for severe symptoms in COPD patients [4]. e CAT is a simple tool comprising eight questions and can distinguish between responses to pulmonary rehabilitation. e CATscore is significantly better in patients with stable COPD than in those with exacerbations [9], and it is negatively correlated with the percent forced expiratory volume in 1 second (FEV1%) [9, 10]. e above assessment approach has certain merits and is more applicable in clinical practice but lacks sufficient objectiveness to reflect the pathological features of COPD patients
Computerized tomography (CT) emphysema index (EI) has been recently reported to be useful in predicting forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) [15]. e low attenuation area (LAA) can be applied to calculate the EI in order to assess the extent of emphysema, which is beneficial for COPD management [16, 17]
Summary
Chronic obstructive pulmonary disease (COPD), a heterogeneous chronic inflammatory airway condition, is one of the leading causes of death with increasing morbidity and mortality worldwide [1, 2]. e definition of COPD is given as a common, preventable, and treatable disease that is characterized by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities, usually caused by significant exposure to noxious particles or gases [3]. e diagnosis and assessment of COPD were mainly based on the pulmonary function according to the Global Initiative for Chronic Obstructive Lung Disease guidelines [4]. Chronic obstructive pulmonary disease (COPD), a heterogeneous chronic inflammatory airway condition, is one of the leading causes of death with increasing morbidity and mortality worldwide [1, 2]. E diagnosis and assessment of COPD were mainly based on the pulmonary function according to the Global Initiative for Chronic Obstructive Lung Disease guidelines [4]. E COPD Assessment Test (CAT) score was recently developed for health status measurements based on the SGRQ [7], which evaluates the impact of symptoms on COPD patients [8]. CB is often the precursor for COPD, which had been reported to increase the severity of the disease (aggravated exacerbations and respiratory mortality) in COPD patients and was considered as a COPD phenotype [20, 21]. Whether the EI can be used to distinguish CB from COPD or to diagnose COPD remains unclear
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