The Prevalence of Asthma-COPD Overlap (ACO) Among Patients with Asthma

Asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) is defined as a persistent airflow limitation with features of both asthma and COPD. However, in Turkey, there are limited data about ACO. The aims of the present study were to determine the prevalence of ACO among patients with asthma, to compare the clinical characteristics of patients with ACO and asthma, and to determine the threshold values for the diagnosis of ACO.

The study group comprised 338 patients admitted to the outpatient clinics between 2010 and 2017 and who had undergone at least three pulmonary function tests within the last 2 years. Patients aged >40 years with a smoking history of >10 pack-years or biomass exposure, with at least three features of both diseases, and with reversible and persistent airflow limitation were diagnosed with ACO. The study is a retrospective study so we did not get informed concent.

Asthma-chronic obstructive pulmonary disease overlap was diagnosed in 40 (11.8%) patients. Patients with ACO had fewer allergic comorbidities, worse spirometric parameters, and required higher doses of inhaled corticosteroids than patients with asthma only (p<0.05). No significant differences were observed between the groups regarding survival or number of hospitalizations and attacks (p>0.05). Threshold values were determined as age ≥57.5 years, smoking history ≥14 pack-years, and diagnosis at age ≥40.5 years.

The frequency of ACO was observed to be very high in patients with asthma. In patients >57.5 years old, with a smoking history of >14.5 pack-years, and diagnosed with asthma at >40.5 years old, the probability of ACO diagnosis increases.