Assessment of bronchodilator responsiveness to salbutamol or ipratropium using different criteria in treatment-naïve patients with asthma and COPD

Background: The criteria for significant bronchodilator responsiveness (BDR) were published in 2005 by the European Respiratory Society/American Thoracic Society, which were revised in 2021, however, data on the agreement between these two recommendations in untreated patients with airflow limitation are missing. Aims: We aimed to study BDR to salbutamol (SABA) or ipratropium bromide (SAMA) in patients with suspected bronchial asthma or COPD at initial clinical presentation using the 2005 and 2021 criteria and explore clinical factors associated with BDR+. Methods: Symptomatic, treatment-na & iuml;ve patients with expiratory airflow limitation (n = 105, 57 men, age (mean +/- standard deviation): 65 +/- 10 years) underwent BDR testing with 400 mcg salbutamol (day 1) or 80 mcg ipratropium bromide (day 2) and BDR was measured after 15 and 30 minutes. Clinical factors with risk for BDR+ were assessed with binomial logistic regression analysis. Results: We found a good agreement between the number of 2005-BDR+ and 2021-BDR+ patients at 15 and 30 minutes post-salbutamol and post-ipratropium (88.6-94.8%). More patients showed BDR+ after 30 minutes than following 15 minutes using either criterion. When results at 30 minutes are considered, the number of patients with 2005-BDR+ (82%) was higher than that of 2021-BDR+ (75%), with the proportion of SAMA+ patients being higher than that of SABA+ (2005: 70% vs. 49%, Fisher exact p < 0.01; 2021: 64% vs. 41%, p = 0.001). 2005-BDR+ and 2021-BDR+ to SABA were associated with decreasing pre-BD FEV1% predicted and the presence of cough. More patients with asthma were in the SABA+ group compared to the SAMA+ group (2005: 71% vs. 53%, Fischer exact p = 0.04; 2021: 77% vs. 52%, p = 0.02). Conclusions: Fewer patients show BDR+ according to the 2021 criteria in comparison with the 2005 recommendations, and protocols for BDR testing may consider the assessment of response to both SABA and SAMA after 30 minutes.