Asthma Masquerading as Chronic Obstructive Pulmonary Disease: A Study of Smokers Fulfilling the GOLD Definition of Chronic Obstructive Pulmonary Disease

Abstract

Background: Irreversible airways obstruction in smokers is usually attributed to chronic obstructive pulmonary disease (COPD). We speculate that some of these are cases of asthma indistinguishable from COPD. Objectives: To determine the prevalence of asthma in a ‘COPD’ population and how to differentiate the two conditions. Methods: This was a prospective observational study of smokers fulfilling the Global Initiative for Chronic Obstructive Lung Disease definition of COPD [mean post-salbutamol forced expiratory volume in 1 s (FEV₁) 66.9% predicted]. They were classified into 4 groups, as follows: (1) inhaled corticosteroid (ICS)-responsive asthma, defined by normalization of spirometry upon ICS treatment; (2) irreversible asthma, defined as airway obstruction for 1 year and bronchial biopsy indicating asthma; (3) COPD, in the presence of bilateral panlobular emphysema with bullae on high-resolution computed tomography, hypercapneic respiratory failure or bronchial biopsy indicating COPD, and (4) unclassified airflow limitation (AFL). Results: Eighty patients fulfilled the definition of COPD. The initial diagnosis was COPD in 57.5% and asthma in 42.5%. The final diagnosis was ICS-responsive asthma in 48 patients (60%), irreversible asthma in 8 (10%), COPD in 16 (20%) and unclassified AFL in 8 (10%). A normal transfer coefficient for carbon monoxide (KCO) and an FEV₁ fluctuation ≧18% during 1 year of follow-up distinguished irreversible asthma and COPD. Seven of the 8 patients with irreversible asthma had improved FEV₁ at the end of 1 year (median 320 ml compared with –29 ml in COPD). Five out of the 8 unclassified AFL cases had normal KCO and a large improvement in FEV₁ suggestive of irreversible asthma. Conclusions: COPD, even in heavy smokers, includes cases of asthma. FEV₁ fluctuation during 1 year is a novel concept which may distinguish irreversible asthma and COPD.

Longitudinal Changes in Clinical Outcomes in Older Patients with Asthma, COPD and Asthma-COPD Overlap Syndrome

“…However, patients with asthma or COPD can share common characteristics, e.g. incompletely reversible airflow obstruction has been observed in a proportion of asthmatics and AHR can occur in patients with COPD [7,8]. The co-existence of these conditions is termed the asthma-COPD overlap syndrome, which is defined when an increased airflow variability occurs together with fixed airflow obstruction.…”

Smoking, asthma, chronic airflow obstruction and COPD

“…Nonsmokers had greater rates of atopy, and elevated exhaled nitric oxide and eosinophil counts, all consistent with asthma. Similarly, AL-KASSIMI et al [19] studied 80 patients in Saudi Arabia aged 40-70 years with >10 pack-years smoking history who fulfilled the spirometric criteria for COPD, with post-bronchodilator FEV1/FVC <0.7 and FEV1 <80% predicted. The initial diagnosis was COPD in 46 (57.5%) patients and asthma in 34 (42.5%).…”

Ashtma-Chronic obstructive pulmonary disease overlap syndrome (ACOS): current evidence and future research directions

“…Quite often the diagnosis can change during life and more authors report about cases of unclassified airflow limitation [16]. Moreover, it has been suggested that ACOS may include not one but several heterogeneous phenotypes with different underlying mechanisms and since these patients were previously excluded from clinical trials we have limited data of this condition [17,18].…”