Introduction: The European Respiratory Society/American Thoracic Society (ERS/ATS) Task Force updated the 2005 recommendations and published new technical standards on spirometry interpretation in 2021.

The aim: To evaluate the impact of the newly established criteria for airway responsiveness in asthma patients.

Material and Methods:  A retrospective cohort study of adult asthma patients referred to spirometry with bronchodilator test at the Institute for Pulmonary Diseases of Vojvodina, Sremska Kamenica, Serbia. We compared the bronchodilator response (BDR) defined by the 2005 and 2021 ERS/ATS criteria and evaluated factors associated with a positive response.

Results: The study included 203 patients, 70 men (34.5%), median age 48 years old (IQR 38-61). A positive BDR test (BDR+) was present in 26.1% of patients both according to 2005 and 2021 criteria. Regarding 2005 criteria, a positive test was based on forced expiratory volume in one second (FEV1) in 22.7% and on forced vital capacity (FVC) in 9.85% of patients, while according to 2021 criteria, positivity was based on FEV1 in 20.7% and on FVC in 13.3% of patients. Overall, there was strong agreement between the 2005 and 2021 ERS/ATS criteria (Kappa 0.84, 95% CI 0.76 to 0.95). Whichever BDR criterion was adopted, BDR+ was associated with age and the degree of airflow obstruction and was not associated with markers of Th2 inflammation.

Conclusion: Compared to 2005 ERS/ATS, the use of 2021 ERS/ATS criteria did not cause a significant change in BDR classification. BDR+ was more common in elderly and patients with low lung function.