Airflow obstruction: is it asthma or is it COPD?

Abstract

Despite the availability of guideline recommendations, diagnostic confusion between COPD and asthma appears common, and often it is very difficult to decide whether the obstruction is caused by asthma or COPD in a patient with airway obstruction. However, there are well-defined features that help in differentiating asthma from COPD in the presence of fixed airflow obstruction. Nonetheless, the presentations of asthma and COPD can converge and mimic each other, making it difficult to give these patients a diagnosis of either condition. The association of asthma and COPD in the same patient has been designated mixed asthma–COPD phenotype or overlap syndrome. However, since the absence of a clear definition and the inclusion of patients with different characteristics under this umbrella term, it may not facilitate treatment decisions, especially in the absence of clinical trials addressing this heterogeneous population. We are realizing that neither asthma nor COPD are single diseases, but rather syndromes consisting of several endotypes and phenotypes, consequently comprising a spectrum of diseases that must be recognized and adequately treated with targeted therapy. Therefore, we must treat patients by personalizing therapy on the basis of those treatable traits present in each subject.

Differences between asthma–COPD overlap syndrome and adult-onset asthma

“…Fixed airflow obstruction due to asthma or COPD has been widely studied. Reports suggest that lower diffusing capacity, lower FeNO levels, higher levels of neutrophils and lower eosinophil counts are evident among patients with fixed obstruction caused by COPD, as compared to those induced by asthma [40][41][42]. However, the differences between ACOS and obstructive asthma have been far less identified [42].…”

“…Reports suggest that lower diffusing capacity, lower FeNO levels, higher levels of neutrophils and lower eosinophil counts are evident among patients with fixed obstruction caused by COPD, as compared to those induced by asthma [40][41][42]. However, the differences between ACOS and obstructive asthma have been far less identified [42]. When comparing obstructive asthma (with a smoking history <10 pack-years) and ACOS in the present study, the results reveal that ACOS most clearly differs from obstructive asthma by a lower diffusing capacity, higher number of comorbidities, and higher levels of neutrophils and IL-6 in the blood.…”

Incidence trends of airflow obstruction among European adults without asthma: a 20-year cohort study

“…The exclusion of the individuals who had reported a diagnosis of asthma at baseline or at the follow-up should have limited the bias due to the asthma-COPD misclassification. Asthma and COPD have a different aetiology, characteristics and clinical course 33 , and AO post-BD in adulthood (even in smokers) should not be considered as COPD without giving consideration to earlier asthma 34 . However, among the incident cases of AO at the 2 nd examination, 61.3% of males and 66.7% of females had either AO or key indicators of COPD 2 or they reported a physician diagnosis of COPD at the 3 rd examination (detailed description available in the Supplementary Information, page 7).…”

Longer duration of asthma is significantly associated with increased RV/TLC ratio

“…Asthma is a clinical syndrome characterized by intermittent or persistent dyspnea, cough and wheeze. Nevertheless, the clinical features of asthma and COPD can overlap making it difficult to differentiate the two syndromes [1] Asthma symptoms have been attributed to airflow obstruction resulting from airway inflammation [2]. Presence of obstruction has been diagnosed by the disproportionate decrease of FEV1 (forced expiratory volume in 1 s) over FVC (forced vital capacity) leading to a low FEV1/FVC ratio.…”