Proportional classifications of COPD phenotypes

Abstract

Background: Chronic obstructive pulmonary disease (COPD) encompasses a group of disorders characterised by the presence of incompletely reversible airflow obstruction with overlapping subsets of different phenotypes including chronic bronchitis, emphysema or asthma. The aim of this study was to determine the proportion of adult subjects aged .50 years within each phenotypic subgroup of COPD, defined as a post-bronchodilator ratio of forced expiratory volume in 1 s/forced vital capacity (FEV 1 /FVC) ,0.7, in accordance with current international guidelines. Methods: Adults aged .50 years derived from a random population-based survey undertook detailed questionnaires, pulmonary function tests and chest CT scans. The proportion of subjects in each of 16 distinct phenotypes was determined based on combinations of chronic bronchitis, emphysema and asthma, with and without incompletely reversible airflow obstruction defined by a post-bronchodilator FEV 1 /FVC ratio of 0.7. Results: A total of 469 subjects completed the investigative modules, 96 of whom (20.5%) had COPD.Diagrams were constructed to demonstrate the relative proportions of the phenotypic subgroups in subjects with and without COPD. 18/96 subjects with COPD (19%) had the classical phenotypes of chronic bronchitis and/or emphysema but no asthma; asthma was the predominant COPD phenotype, being present in 53/96 (55%). When COPD was defined as a post-bronchodilator FEV 1 /FVC less than the lower limit of normal, there were one-third fewer subjects with COPD and a smaller proportion without a defined emphysema, chronic bronchitis or asthma phenotype. Conclusion: This study provides proportional classifications of the phenotypic subgroups of COPD which can be used as the basis for further research into the pathogenesis and treatment of this heterogeneous disorder.

Quality of life measured by the St George's Respiratory Questionnaire and spirometry

“…There is a high prevalence of asthma in New Zealand and some of the subjects identified as having COPD from post-bronchodilator spirometry may actually have asthma with incomplete bronchodilator reversibility rather than COPD. In a separate analysis of the WRS data, ,25% of subjects identified as having COPD had features of asthma and no apparent chronic bronchitis or emphysema [24]. As the proportion of these individuals that have COPD with an asthma-like phenotype and the proportion that have ''pure'' asthma cannot be determined, individuals with an asthma-like phenotype of airway disease were not excluded from the analysis.…”

“…The use of the FEV1 80, 60 and 40% pred cut-off points would also have the advantage of consistency with the grading of severity for asthma [17]. In support of this approach, many older patients with asthma will meet the spirometrically-defined criteria for COPD [24].…”

Asthma‐COPD overlap syndrome—Coexistence of chronic obstructive pulmonary disease and asthma in elderly patients and parameters for their differentiation

“…showed prevalence of ACOS patients by gender increased depending on aging. Guidelines2, 4 showed the prevalence rates of ACOS have ranged between 15% and 55%,6, 7, 8 and concurrent doctor‐diagnosed asthma and COPD have been reported in between 15% and 20% of patients 9, 10, 11, 12. In Japan, Nagai et al 13.…”

Relationship between Lung Functions and Extend of Emphysema in Patients with Chronic Obstructive Pulmonary Disease

“…Chronic obstructive pulmonary disease is very inhomogeneous condition and a better characterization of the phenotype of disease may help to reduce the variability of response to therapeutic interventions in COPD patients [12]. Spirometry is widely used to evaluate the presence and severity of airway obstruction, while the assessment of emphysema by HCRT scan is restricted to those patients who are possible candidates for surgery [13].…”