Concern of underdiagnosing asthma–COPD overlap syndrome if age limit of 40 years for asthma is used

From the authors:

M. Tommola and colleagues raise an important and hotly debated diagnostic criterion of asthma–chronic obstructive pulmonary disease overlap syndrome (ACOS): an age threshold of 40 years for the asthma component of ACOS. We agree with their comment that asthma can develop later in life and these patients may respond well to inhaled corticosteroids and novel biologics, similar to those with childhood-onset asthma [1]. Thus, in the roundtable consensus report [2], we suggested that the asthma component of ACOS could be fulfilled by a clinical diagnosis of asthma before age 40 years or in those without a clinical diagnosis of asthma before 40 years by demonstrating an improvement in forced expiratory volume in 1 s (FEV₁) of ≥400 mL following short-acting β₂-agonist therapy. While a significant bronchodilatory response (BDR) is a common feature in both asthma and chronic obstructive pulmonary disease (COPD) [3], it is very unusual for COPD patients to demonstrate a BDR of ≥400 mL in FEV₁ without a concomitant diagnosis of asthma [4]. To further improve the specificity of the asthma component of ACOS, we also suggested that in addition to all three major criteria, patients fulfil at least one of the three minor criteria: 1) a history of atopy or allergic rhinitis; 2) a BDR of ≥200 mL in FEV₁ on two separate visits; or 3) peripheral eosinophil count of ≥300 cells per μL. While none of these criteria has been validated in ACOS, we believe that these criteria are clinically workable and may be useful in identifying patients with asthma with reasonable precision. Future work will be needed to refine these criteria based on high-grade data.

Disclosures