Assessing the Impact of the Updated 2021 European Respiratory Society/American Thoracic Society Criteria on Bronchodilator Responsiveness in Asthma.

Introduction The European Respiratory Society/American Thoracic Society (ERS/ATS) Task Force released new technical standards on spirometry interpretation in 2021. Our study compares bronchodilator responsiveness (BDR) in asthma, evaluating the impact of the 2005 and 2021 ERS/ATS criteria and the influence of predictive equations. Methods A retrospective cohort study of adult patients with asthma was referred to spirometry with a BDR test at the Institute for Pulmonary Diseases of Vojvodina, Sremska Kamenica, Serbia. The study included adult patients with asthma who underwent BDR testing in the Department of Respiratory Pathophysiology at the institute and had available data on height, gender, age, race, and eosinophil count. Results Among 197 patients, 69 were men (35.0%), the median age was 47 years (interquartile range (IQR) 38-60), and a positive BDR test occurred in 50 (25.38%) according to the 2005 criteria and 42 (21.32%) according to 2021 criteria when using the Global Lung Initiative (GLI) reference equations. Strong agreement was observed between the ERS/ATS 2005 and 2021 criteria (Cohen's kappa index: 0.887, 95%, CI 0.810 to 0.963). Similar results were found with the Third National Health and Nutrition Examination Survey (NHANES III) and the European Community of Coal and Steel (ECCS) predictive equations. Positive BDR tests were common in patients with moderately severe and severe forced expiratory volume in one second (FEV1) impairment and were not associated with eosinophil count or total serum immunoglobulin E (IgE) levels. Conclusion The introduction of the 2021 ERS/ATS criteria did not significantly alter the classification of BDR in the majority of asthma patients, ensuring diagnostic stability. Whichever criterion was used, positive BDR correlated with the extent of FEV1 impairment, but not asthma biomarkers.