Bronchodilator Responsiveness and Clinical Outcomes in Patients with Chronic Obstructive Pulmonary Disease

Introduction: Chronic obstructive pulmonary disease (COPD) is characterized as expiratory airflow limitation in individuals with significant smoking history. Bronchodilator responsiveness (BDR) might be shown in some COPD patients and might be associated with clinical outcomes. Objectives: To determine the BDR prevalence and the correlation between BDR and clinical outcomes in COPD patients. Methods: A cross-sectional study was conducted on stable COPD patients at Thammasat University Hospital between March 2019 and January 2022. Demographics, respiratory symptoms and functional capacity assessed by modified Medical Research Council, COPD Assessment Test, 6-minute walking distance, clinical outcomes (exacerbation, hospitalization, rescue medication use), and pulmonary functions were recorded. BDR criteria were defined according to the following established guidelines: the American College of Chest Physicians (ACCP), the European Respiratory Society (ERS), and the American Thoracic Society/European Respiratory Society (ATS/ERS). Results: A total of 150 patients were included. Mean age was 75.2 ± 8.5 years. Post-BD FEV1 was 65.6 ± 24.0%. Prevalence of BDR was 30.7% (ERS), 25.3% (ATS/ERS), and 16.0% (ACCP). BDR did not significantly correlate with respiratory symptoms, functional capacity, or clinical outcomes. Nevertheless, the pulmonary function data showed the BDR group had less severe airway obstruction than the non-BDR group (pre-BD FEV1 in 72.4 ± 25.0% vs 63.3 ± 23.3%, P = 0.045). Conclusions: Bronchodilator responsiveness in COPD was a common condition. However, there was no correlation between BDR and clinical outcomes. A large prospective cohort study is needed to investigate this relationship and demonstrate the mortality outcome.