The local prevalence of COPD by post-bronchodilator GOLD criteria in Korea

OBJECTIVE: Chronic obstructive pulmonary disease (COPD) is a disease characterised by not fully reversible airflow limitation. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) committee decided to diagnose COPD using post-bronchodilator spirometry values. We aimed to examine the prevalence and risk factors of COPD in Ansan, an industrialised city of Korea, by using the post-bronchodilator GOLD criteria. We then investigated the implications of bronchodilation on the prevalence of COPD. DESIGN: A total of 3642 participants in the Korean Health and Genome Study were interviewed about age, income, smoking status and respiratory symptoms and completed pulmonary function tests, including post-bronchodilator spirometry. RESULTS: COPD prevalence by post-bronchodilator spirometry was 3.7% (134/3642), which was significantly different from that estimated using pre-bronchodilator criteria (7.7%, 282/3642). Exclusion of subjects with significant bronchodilator response (BDR) significantly lowered the prevalence of COPD to 3.3% (117/3572), compared with including subjects with post-bronchodilatory residual obstruction with significant BDR. Prevalence was associated with old age, smoking history, male sex and respiratory symptoms. CONCLUSION: COPD prevalence by post-bronchodilator GOLD criteria was 3.7%, which was much lower than that of pre-bronchodilator criteria. The bronchodilator reversibility test substantially affects estimations of COPD prevalence.