Characterisation of phenotypes based on severity of emphysema in chronic obstructive pulmonary disease

Abstract

Background: Airflow limitation in chronic obstructive pulmonary disease (COPD) is caused by a mixture of small airway disease and emphysema, the relative contributions of which may vary among patients. Phenotypes of COPD classified purely based on severity of emphysema are not well defined and may be different from the classic phenotypes of ''pink puffers'' and ''blue bloaters''. Methods: To characterise clinical phenotypes based on severity of emphysema, 274 subjects with COPD were recruited, excluding those with physician-diagnosed bronchial asthma. For all subjects a detailed interview of disease history and symptoms, quality of life (QOL) measurement, blood sampling, pulmonary function tests before and after inhalation of salbutamol (0.4 mg) and high-resolution CT scanning were performed. Results: Severity of emphysema visually evaluated varied widely even among subjects with the same stage of disease. No significant differences were noted among three groups of subjects classified by severity of emphysema in age, smoking history, chronic bronchitis symptoms, blood eosinophil count, serum IgE level or bronchodilator response. However, subjects with severe emphysema had significantly lower body mass index (BMI) and poorer QOL scores, evaluated using St George's Respiratory Questionnaire (SGRQ), than those with no/mild emphysema (mean (SD) BMI 21.2 (0.5) vs 23.5 (0.3) kg/m 2 , respectively; SGRQ total score 40 (3) vs 28 (2), respectively; p,0.001 for both). These characteristics held true even if subjects with the same degree of airflow limitation were chosen. Conclusions: The severity of emphysema varies widely even in patients with the same stage of COPD, and chronic bronchitis symptoms are equally distributed irrespective of emphysema severity. Patients with the phenotype in which emphysema predominates have lower BMI and poorer health-related QOL.

Functional single nucleotide polymorphisms of theCCL5gene and nonemphysematous phenotype in COPD patients

“…The method of computerised assessment of emphysema for the whole lung has been described previously and is given in detail in the supplementary material. A strong correlation between the two methods of assessment was found (n5137; r50.835; p,0.0001) [16].…”

“…Among 274 patients with COPD recruited for the Hokkaido COPD cohort study [16], a total of 267 patients, for whom genetic samples were available, were examined in the present study. Study approval was obtained from governing ethics committees for each study centre, and all subjects provided written informed consent.…”

“…Information regarding the computed tomography (CT) scanners and parameters assessed has been described previously [16]. The severity of emphysema was assessed visually by three independent pulmonologists according to the modified [16] scoring system of GODDARD et al [17]; the pulmonologists were blinded to any clinical information regarding the patient.…”

“…The severity of emphysema was assessed visually by three independent pulmonologists according to the modified [16] scoring system of GODDARD et al [17]; the pulmonologists were blinded to any clinical information regarding the patient. Six images in three slices were analysed in the lungs, including the aortic arch, the carina and 1-2 cm above the highest hemidiaphragm.…”

“…In the present study, using a well-characterised COPD cohort of Japanese subjects [16], the specific hypothesis that functional single nucleotide polymorphisms (SNPs) in the regulatory region of CCL5 and their haplotypes have a genetic impact upon the variable expression of the emphysematous phenotype in patients with COPD was examined.…”