Can't Catch a Breath

Feb 21 2019

I spent the day in the Asthma and Airway Clinic today and had the opportunity to see several different bread-and-butter respirology cases, including COPD, asthma, and occupational-related lung diseases. During the morning, I saw a patient that had been referred for a possible diagnosis of COPD. He had experienced progressively worsening dyspnea over the last few years, and described feeling that he could not "catch enough air in a breath". The patient had a significant smoking history, as well as long-term exposure to occupational irritants in his work in construction. Although he had no history of asthma, he remembered being prescribed puffers in the past. His pulmonary function testing showed an obstructive pattern with no significant bronchodilator response. In discussing this case with my preceptor, we were quite certain this patient had COPD. However, my staff also raised the possibility of asthma-COPD overlap given some of his other characteristics.

Asthma-COPD overlap (ACO) is the presence of clinical features of both asthma and COPD, and is often not well recognized. There have been many different definitions of ACO over the years and thus the prevalence is difficult to determine exactly. The COPDGene study used the co-existence of diagnostic codes of asthma and COPD in the clinical history of the same patient and found a prevalence of 13% of this overlap. The study also found that asthma-COPD overlap was associated with an increased risk of exacerbations and hospitalizations (1). The Global Initiative for Chronic Obstructive Lung Disease (GOLD) developed a consensus document proposing that in order to diagnose ACO, 3 characteristics of asthma and 3 of COPD (taken from a list) should be fulfilled (2). In any case, numerous studies have demonstrated that ACO is a heterogenous disorder.

Management of ACO is challenging since these patients are often intentionally excluded from clinical trials. In addition, the heterogeneity of this syndrome makes it difficult to have a single approach to the management of all patients. General non-pharmacologic principles of management are not unlike those for COPD and asthma and include: smoking cessation, up-to-date vaccinations, proper inhaler technique, avoidance of allergens, and pulmonary rehabilitation. In terms of pharmacotherapy, all patients with ACO should have access to a rapid-acting inhaled bronchodilator (SABA, SAMA or combination) for as-needed symptom relief. Regular therapy with an inhaled corticosteroid is important in these patients. The addition of a long-acting beta-agonist (LABA) or long-acting muscarinic antagonist (LAMA) may be necessary to help adequately manage symptoms. Therapy can be escalated to help maintain control of symptoms. An important principle of ACO management is to avoid LABA monotherapy without inhaled corticosteroids.

Through this case, I was able to learn more about the complex entity of asthma-COPD overlap and will keep this diagnosis in  mind when I see patients that have features consistent with both of these conditions!

-MB-

References:

1. Hardin M, Silverman EK, Barr RG, et al. The clinical features of the overlap between COPD and asthma. Respir Res 2011; 12(1): 127-135.
2.  Vogelmeier CF, Criner GJ, Martinez FJ, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive lung disease 2017 report: GOLD executive summary. Arch Bronconeumol 2017; 53: 128–149.