Differential Diagnosis

COPD and asthma are two distinct diseases with fundamental differences that influence both diagnosis and treatment.1,2 Despite this, some characteristics of both conditions may coexist in a given patient and this is currently termed asthma-COPD overlap syndrome (ACOS).5

Differentiation between asthma and COPD is extremely important as treatment strategies and prognoses differ for the two conditions.

Characteristics that differentiate COPD and asthma are summarised in Table 1.

Table 1. Key differentiators between COPD and asthma1,2,6

Key differentiators between COPD and asthma.


Historically, the differential diagnosis of asthma and COPD has been poor, largely due to a lack of awareness of COPD and the limited use of spirometry at the primary care level. However, it is critically important that these conditions are correctly differentiated to ensure that patients are treated with appropriate medications. Misdiagnosis of either condition can lead to inappropriate treatment. Correct diagnosis of COPD will help to ensure patients are given access to pulmonary rehabilitation, a key aspect of COPD management.1,2,6 Patients with asthma may require anti-inflammatory medication, such as inhaled corticosteroids (ICS), for optimal control of their symptoms. In contrast, in patients with COPD and low risk of exacerbations, ICS provide little benefit and may increase the risk of adverse events such as pneumonia. Therefore, ICS are not recommended for patients with COPD and a low risk of exacerbations. 

Despite the challenges faced in differentiating COPD from asthma, accurate diagnosis of these distinct conditions is imperative to ensure optimal management strategies are instigated. Further information can be found in the guidelines section.