European Journal of Cardiovascular Medicine

Asthma and chronic obstructive pulmonary disease (ACO) had been previously considered as two different disease entities, but recently it was found that some patients have features of both asthma and chronic obstructive pulmonary disease (COPD). ^[1] ACO is identified by persistent airflow limitation with several features usually associated with asthma and several features usually associated with COPD. ^[2]

It has been suggested that patients with ACO may have special characteristics such as greater airway hyperresponsiveness, higher sputum and blood eosinophils and better response to inhaled corticosteroids (ICS) than patients with COPD. ^[3] History of atopy, eosinophilic inflammation and serum IgE had been emphasized by Hattori to identify patients with ACO among those with COPD. ^[4]

Asthma-like symptoms: Wheezing, cough, and shortness of breath, often variable and triggered by allergens or irritants. COPD-like features: Persistent airflow limitation and progressive dyspnea, typically associated with smoking or long-term exposure to harmful particles (e.g., environmental pollution, occupational hazards). Exacerbations: Patients may experience more frequent exacerbations than those with asthma or COPD alone. ^[5]

The prevalence of ACOS among patients with obstructive airway diseases varies widely depending on the population studied and the diagnostic criteria used. Estimates suggest that 15% to 20% of patients with COPD may have features of asthma, and conversely, 20% to 30% of asthma patients may also show signs of COPD. ^[6] Overall, the prevalence of ACOS in the general population is estimated to be around 5% to 10% of individuals with obstructive airway diseases. ^[7] Prevalence in Asthma and COPD Populations: Among asthma patients, about 10% to 20% may also meet the criteria for COPD. Among COPD patients, 15% to 30% may have features consistent with asthma, especially if they have a history of childhood asthma or significant. ^[8]

Aim

The aim is to study the characteristics features of ACO, to assess its percentage among obstructive airway diseases and to assess sputum eosinophils in these patients.

This cross‑sectional study included outpatients who applied to our pulmonology outpatient clinic with the previous diagnosis of asthma and COPD. Outpatients who had a confirmed diagnosis of asthma or COPD in hospital data according to GOLD and GINA. ^[9] Guidelines were evaluated to determine whether they met the ACO criteria. GINA‑GOLD, Spanish, and American Thoracic Society (ATS) Guidelines were used for the diagnostic assessment of ACO. ^[10]

According to GINA‑GOLD report, patients with airflow limitations who have both three or more features favoring asthma, and three or more features favoring COPD, meet the criteria for ACO. ^[11]

The consensus report on ACO between Spanish guidelines ^[12] shows that diagnosis of ACO is confirmed when a patient (35 years of age or older) is a smoker or ex‑smoker of more than 10 pack‑years and presents with airflow limitation (postbronchodilator forced expiratory volume in 1 s [FEV1]/Forced vital capacity <0.7) and has an objective current diagnosis of asthma. In cases with no asthma diagnosis, significant positive results on a bronchodilator test (FEV1 ≥15% and ≥400 mL) or elevated blood eosinophil count (≥300 eosinophils/μL) will also support the diagnosis of ACO.

ATS Roundtable criteria ^[13] are as follows: Major criteria: Persistent airflow limitation, age ≥40 years, smoking ≥10 pack‑years, air pollution exposure, documented asthma history before 40 years of age, or bronchodilator response (BDR) >400 mL; and minor criteria: Documented atopy or allergic rhinitis history, two separate BDR >12% and 200 mL, and blood eosinophil count over 300/μL. Participants with three major criteria and at least 1 min or criterion were accepted as ACO according to ATS roundtable criteria.

The demographic data and evaluation parameters about ACO, such as a history of childhood asthma, presence of atopy, eosinophilic status of blood, smoking status, and spirometry values, were collected according to face‑to‑face meetings and medical records. The patients with incomplete data about the diagnostic criteria of ACO were excluded.

Patients were divided into three groups following evaluation of ACO criteria such as the asthma group, the COPD group, and the ACO group. The characteristics and some parameters of these three groups were compared.

Statistical analysis

Statistical analyses were performed using the Statistical Package for the Social Sciences version 25.0 software. The continuity correction Chi‑square test and Fisher’s exact test were used in the comparison of the frequency rates of categorical variables between groups of asthma/ACO and COPD/ACO. The nonparametric Kruskal–Walli’s test was applied for multiple comparisons when the Mann–Whitney U‑test was used for comparison between the groups. The Pearson correlation was used to assess the strength of the linear relationship between two variables. A paired sample t‑test was used to compare the means of the groups. A P < 0.05 was considered statistically significant

This cross‑sectional study included outpatients who applied to our pulmonology outpatient clinic with the previous diagnosis of asthma and COPD. Outpatients who had a confirmed diagnosis of asthma or COPD in hospital data according to GOLD and GINA. ^[9] Guidelines were evaluated to determine whether they met the ACO criteria. GINA‑GOLD, Spanish, and American Thoracic Society (ATS) Guidelines were used for the diagnostic assessment of ACO. ^[10]

According to GINA‑GOLD report, patients with airflow limitations who have both three or more features favoring asthma, and three or more features favoring COPD, meet the criteria for ACO. ^[11]

The consensus report on ACO between Spanish guidelines ^[12] shows that diagnosis of ACO is confirmed when a patient (35 years of age or older) is a smoker or ex‑smoker of more than 10 pack‑years and presents with airflow limitation (postbronchodilator forced expiratory volume in 1 s [FEV1]/Forced vital capacity <0.7) and has an objective current diagnosis of asthma. In cases with no asthma diagnosis, significant positive results on a bronchodilator test (FEV1 ≥15% and ≥400 mL) or elevated blood eosinophil count (≥300 eosinophils/μL) will also support the diagnosis of ACO.

ATS Roundtable criteria ^[13] are as follows: Major criteria: Persistent airflow limitation, age ≥40 years, smoking ≥10 pack‑years, air pollution exposure, documented asthma history before 40 years of age, or bronchodilator response (BDR) >400 mL; and minor criteria: Documented atopy or allergic rhinitis history, two separate BDR >12% and 200 mL, and blood eosinophil count over 300/μL. Participants with three major criteria and at least 1 min or criterion were accepted as ACO according to ATS roundtable criteria.

The demographic data and evaluation parameters about ACO, such as a history of childhood asthma, presence of atopy, eosinophilic status of blood, smoking status, and spirometry values, were collected according to face‑to‑face meetings and medical records. The patients with incomplete data about the diagnostic criteria of ACO were excluded.

Patients were divided into three groups following evaluation of ACO criteria such as the asthma group, the COPD group, and the ACO group. The characteristics and some parameters of these three groups were compared.

Statistical analysis

Statistical analyses were performed using the Statistical Package for the Social Sciences version 25.0 software. The continuity correction Chi‑square test and Fisher’s exact test were used in the comparison of the frequency rates of categorical variables between groups of asthma/ACO and COPD/ACO. The nonparametric Kruskal–Walli’s test was applied for multiple comparisons when the Mann–Whitney U‑test was used for comparison between the groups. The Pearson correlation was used to assess the strength of the linear relationship between two variables. A paired sample t‑test was used to compare the means of the groups. A P < 0.05 was considered statistically significant

This study was conducted on 90 patients with chronic airway diseases (COPD, asthma and asthma COPD overlap) were selected. It included 72 (80%) males and 18 (20%) females Table 1.

Table 1 Sex distribution among the study group

Table 2 Classification of study groups based on final diagnosis

ACO: Asthma chronic obstructive pulmonary disease overlap;

COPD: Chronic obstructive pulmonary disease.

Among the studied participants, 36 (40%) patients were diagnosed as having ACO, 23 (25.6%) patients were diagnosed as having asthma and 31 (34.4%) patients as having COPD (Table 2).

Table 3 Age differences between the study group

Regarding the age difference between groups, it was found that patients who were diagnosed as having ACO were older than asthmatic patients with mean age of 53.48±8.38 and 41.58±6.28 years, respectively. The men age of patients with COPD was 56.29±8.32 which was older than both ACO and asthmatic patients (Table 3).

Table 4 Comparison of studied groups regarding history of atopy

Table 4 showed the comparison of groups regarding history of atopy. We found that 55.6% of ACO group, 73.9% of asthma group and 29.1% of COPD group had a positive history of atopy.

Table 5 Comparison of study groups regarding sputum eosinophils

We found that 66.7% of ACO group, 69.6% of asthma group and 74.2% of COPD group had a positive history of atopy. Comparison of study groups regarding sputum eosinophils revealed that 33.3% of ACO group, 30.4% of asthma group and 25.8% of COPD group had positive sputum eosinophils (Table 5).

The current study looked at the clinical phenotype and prevalence of ACO among patients with chronic airflow obstruction. ACO was found in 16.3% of patients with chronic airflow obstruction, which is comparable to the prevalence reported in the literature (15-25%). ^[14] Since different criteria have been employed across studies evaluating different demographic groups (patients with COPD, patients with airway obstruction, the general population, different age groups), the reported prevalence of ACO differs from study to study. ^[15]

In the current study, all patients with ACO presented with shortness of breath. The observed prevalence of wheeze, cough, and expectoration was less than that was observed in previous studies, possibly due to inconsistency in the reporting of the symptoms because of regional or environmental impact. ^[16] Most of the patients with ACO in our study showed intermittent (64.9%) and progressive (76.6%) pattern of symptoms while 96.1% of patients had seasonal and diurnal variability. This pattern of symptoms is expected from the ACO population as they exhibit features of both asthma and COPD.

ACO patients had significantly higher CCQ scores compared to COPD patients in our study. This points toward higher symptom frequency, severity and lower health status in ACO patients than in COPD patients. Kauppi and Corlateanu evaluated the health-related quality of life in patients with chronic airway obstruction and different phenotypes of COPD respectively. According to these studies, patients with ACO had worse health-related quality of life (HRQoL) than asthma patients, whereas frequent exacerbator COPD patients had more severe deterioration of HRQoL and worse lung function than patients with ACO. Furthermore, ACO patients had a significantly higher exacerbation rate than COPD patients which is in accordance with the observations of Hardin, Miravitlles and Menezes. ^[17]

All ACO patients had a post-bronchodilator increase in FEV1 of more than 200 ml and 12%, while more than half (51.9%) had a post-bronchodilator increase in FEV1 of more than 400 ml and 12%. These values of post-bronchodilator change in spirometry parameters were expected in the ACO group as it is required for its diagnosis in the syndromic approach to chronic airway diseases. ^[18] The increase in FEV1 postbronchodilator was significantly larger than that observed in COPD patients, as patients with ACO show marked postbronchodilator reversibility (p<0.001).

We discovered that COPD patients had a higher prevalence and extent of emphysema on HRCT than ACO patients. This is consistent with previous research comparing ACO and COPD. ^[19] The COPD group had significantly higher parameters of lung hyperinflation, vascular attenuation, and vascular distortion than the ACO group. The parameters of lung hyperinflation described in our study had not previously been studied in the ACO population. Major airway wall thickness, a chronic bronchitis indicator, was higher in ACO patients but not statistically significant.

Suzuki, discovered that airway wall thickness was significantly higher in ACO than in COPD, and that it decreased after treatment with budesonide/formoterol. However, the subjects in this study were much older than those in the current study. In their study on the COPD gene cohort, Cosentino, discovered that patients with ACO had more airway disease, as evidenced by a greater segmental wall area and thickness when compared to COPD patients. Despite the fact that the ACO patients in this study were significantly younger than the COPD patients. Another recent study on the Egyptian population found that patients with asthma had significantly greater airway wall thickness compared to the ACO and COPD groups (p<0.001). ^[20]

Many patients who have asthma or COPD have symptoms from both diseases. The use of a syndromic approach to chronic airway diseases may result in the diagnosis of ACO in many patients who were previously treated for COPD or asthma. According to the findings of this study, patients with ACO have a distinct phenotype in terms of clinical presentation and HRCT features. HRCT features may aid in distinguishing ACO patients from COPD and asthma patients and may be included in future ACO diagnostic guidelines.

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