Asthma and chronic obstructive pulmonary disease

Abstract

Purpose of review: In the clinical setting, patients who present with a combination of asthma and chronic obstructive pulmonary disease (COPD)-related traits are not uncommon. This review discusses recent advances in the characterization of the natural course, phenotypes, and molecular markers of cases with coexisting asthma and COPD and in the understanding of the nature of the link between these two conditions.

Recent findings: Recent epidemiological evidence indicates that asthma accounts for a substantial proportion of cases of irreversible airflow limitation in the general population and that, in addition to the critical role of environmental exposures in adult age, alterations of developmental processes in childhood may also predispose patients with asthma to COPD later in life. Findings from clinical and experimental studies emphasize the existence of remarkable heterogeneity within the group of patients with coexisting asthma and COPD in terms of natural history of lung function, risk factors for disease progression, lung structural changes, and immunological profiles.

Summary: The phenotypic complexity of cases with coexisting asthma and COPD challenges a rigid categorization of patients into existing diagnostic labels and suggests the importance of integrating clinical, functional, morphologic, immunological, and molecular assessments to tailor and optimize prevention and treatment.

Figure 1. Proportional Venn diagram depicting the overlap of asthma, chronic bronchitis, emphysema, and COPD in the Wellington Respiratory Survey

[reproduced with permission from ref(14)] Data refer to 469 participants (age 25 to 75 years) with completed information. The rectangle represents the entire study population; the clear circles within each area represent the proportion of subjects with COPD (post-bronchodilator FEV1/FVC ratio < 0.7); and the isolated clear circle represents participants with COPD who did not meet criteria for any additional phenotype of asthma, chronic bronchitis, or emphysema.

Figure 2. Natural history of lung function among participants in the TESAOD Study

[reproduced with permission from ref(24)] The natural history of lung function of participants who developed persistent airflow limitation (i.e., an FEV1/FVC ratio consistently lower than 0.7 in multiple surveys) was studied over the span of adult life, according to whether or not they had a physician-confirmed diagnosis of asthma. Results are shown for the groups of subjects with 1) no asthma and persistent airflow limitation; 2) asthma onset > 25 years and persistent airflow limitation; 3) asthma onset ≤ 25 years and persistent airflow limitation. The line on top represents predicted values for subjects with no asthma and no airflow limitation. Depicted values represent predicted FEV1 values for a 175-cm tall male from the best fitting random coefficients model.