What are the diagnostic criteria for Asthma-Chronic Obstructive Pulmonary Disease (COPD) overlap?

From the Guidelines

Diagnosing Asthma-COPD Overlap (ACO) requires a stepwise approach, starting with clinical history, physical examination, and radiology, followed by a syndromic approach to identify features of asthma and COPD, and finally, confirmation with spirometry, as recommended by the GINA/GOLD consensus document 1. To diagnose ACO, healthcare providers should look for features of both asthma and Chronic Obstructive Pulmonary Disease (COPD) in the same patient. This typically includes:

• Conducting spirometry tests to measure lung function, specifically looking for airflow limitation with an FEV1/FVC ratio less than 0.7, which indicates obstruction
• Assessing for bronchodilator reversibility (improvement of FEV1 by at least 12% and 200 mL after bronchodilator administration), which suggests an asthma component, while persistent airflow limitation points to COPD
• Evaluating medical history, including smoking history (typically associated with COPD), history of allergies or atopy (suggesting asthma), age of symptom onset (asthma often begins earlier in life), and pattern of symptoms (variability suggests asthma, while persistence suggests COPD)
• Considering additional tests, such as eosinophil counts in blood or sputum (elevated in asthma), FeNO (fractional exhaled nitric oxide) measurement to detect airway inflammation, chest imaging to rule out other conditions, and allergy testing if an allergic component is suspected The Spanish COPD consensus document suggests using major and minor criteria to diagnose ACO, including increase in FEV1 ≥15% and ≥400 mL, eosinophilia in sputum, and a history of asthma as major criteria, and elevated total IgE, history of atopy, and positive bronchodilator response as minor criteria 1. The most recent and highest quality study, the 2018 GOLD report, emphasizes the importance of high-quality spirometry for the diagnosis of COPD, and recommends a fixed FEV1/FVC ratio of less than 0.70 to define COPD 1. However, the diagnosis of ACO should prioritize the identification of features of both asthma and COPD, and the use of a syndromic approach to diagnose the overlap syndrome, as recommended by the GINA/GOLD consensus document 1. The treatment of ACO typically requires inhaled corticosteroids combined with long-acting bronchodilators to address both inflammatory and obstructive components, and should be individualized based on the patient's specific needs and response to treatment.

From the Research

Diagnostic Criteria for Asthma-COPD Overlap

To diagnose asthma-COPD overlap, the following criteria can be considered:

• Airflow obstruction with a strong although incomplete reversibility to bronchodilation tests 2
• Significant exposure to cigarette or biomass smoke 2
• History of atopy or asthma 2
• Eosinophilic airway and systemic inflammation 2
• Good response to corticosteroid treatment 2
• High concentration of exhaled nitric oxide 2

Spirometric Evaluation

Spirometric evaluation is essential in diagnosing asthma-COPD overlap:

• Postbronchodilator spirometry is necessary to confirm a new diagnosis of COPD 3
• Prebronchodilator spirometry should be performed for the diagnosis of asthma 3
• An increase in FEV1 after bronchodilator >400 mL can be used to diagnose ACOS in patients without a documented history of asthma before 40 years of age 2

Algorithm for Diagnosis

A novel algorithm for ACO diagnosis has been proposed by the Spanish Respiratory Society (SEPAR) 4:

• Presence of chronic airflow limitation in a smoker or ex-smoker patient ≥35 years old
• Current diagnosis of asthma
• Very positive bronchodilator test (PBT; ≥15% and ≥400 ml) or presence of eosinophilia in blood (≥300 eosinophils/μl)

Clinical Considerations

Clinical considerations for diagnosing asthma-COPD overlap include:

• Distinguishing ACOS from asthma with not fully reversible bronchial obstruction due to airway remodeling 2
• Recognizing that the lack of smoking exposure should exclude the diagnosis of ACOS 2
• Understanding that the prevalence of ACOS increases with aging, then remains relatively stable in elderly individuals (>65 years) 2