Study Tests Whether Asthma–COPD Overlap Is a Heterogeneous Condition

Asthma—COPD overlap (ACO) is a term that encompasses patients with characteristics of 2 conditions, asthma and chronic obstructive pulmonary disease (COPD). A recent study from Spain sought to validate a proposed algorithm to help clinicians identify ACO among patients with COPD, in an effort to tailor treatment.

The proposed algorithm requires the diagnosis of COPD based on current guidelines. It also prompts the clinician to consider the diagnosis of ACO in 3 different scenarios:

• if the patient has also a previous diagnosis of asthma
• if the patient presents a high bronchodilator response (HBR, defined as a change of >400 mL and >15% in forced expiratory volume in 1 second [FEV₁]), and/or
• a significant blood eosinophil count (≥300 cells/μL)

The study sought to test whether or not ACO is a heterogeneous condition due to the combination of 2 illnesses with different underlying mechanisms, prognoses, and therapeutic needs. It sought to compare the prevalence, clinical characteristics, lung function, laboratory data, and prognosis of patients classified as having ACO from the 3 different approaches recommended by the algorithm.

Researchers used data from the Majorca Real-Life Investigation in COPD and Asthma (MAJORICA) cohort, which contains combined data from 3 sources—a primary care database, hospital electronic charts, and electronic prescription system—covering the residents of the Balearics islands in Spain (±1.1 million subjects). The MAJORICA cohort includes data from all patients 18 years and older with a primary care diagnosis of asthma and/or COPD in 2012 (n = 68,578). All demographics, clinical data, laboratory tests, lung function, and resource use and pharmacy dispensing data for the period between 2012 and 2015 were extracted.

They included patients who were 40 years or older and had smoking exposure greater than 10 pack-years, spirometry-confirmed postbronchodilator airflow obstruction (FEV₁/forced vital capacity, percent predicted [FVC] <0.7), at least 1 eosinophil count in 2014, and follow-up until 2015.

Of the 603 patients, the prevalence rates of asthma and smoking history, COPD with high bronchodilator response, and eosinophilic COPD were 14%, 1.5%, and 12%, respectively.

Those with an asthma and smoking history were younger and used more rescue inhalers, corticosteroids, and health resources. Those with eosinophilic COPD were older, were often treated with corticosteroids, and had lower use of health resources. Most of the patients with COPD with high bronchodilator response were included in the eosinophilic COPD group.

The researchers said they validated the algorithm to differentiate a specific phenotype of COPD, finding that 27.4% of all patients with COPD fulfilled the definition of ACO, and these patients were more frequently treated with inhaled corticosteroids. Patients with eosinophilic COPD are different from those patients with COPD with a previous diagnosis of asthma, they said, and clinicians should consider this during treatments.

This differs from current guidelines, which recommends combining 3 characteristics of asthma and 3 of COPD to make a diagnosis of overlap a homogeneous condition.

Reference

Toledo-Pons N, van Boven JFN, Román-Rodríguez M, Pérez N, Valera Felices JL, Soriano JB. ACO: time to move from the description of different phenotypes to the treatable traits [published online January 24, 2019]. PLOS One. doi: 10.1371/journal.pone.0210915.