Prevalence and risk factors of airflow obstruction in Southwest China: baseline findings from a multi-center population-based cohort study

Chronic obstructive pulmonary disease (COPD) is a progressive respiratory disorder primarily characterized by persistent airflow obstruction. This study investigates the prevalence and risk factors of pre-bronchodilator airflow obstruction among general population aged 40 years or older in Southwest China. This is a cross-sectional baseline analysis of an ongoing multi-center population-based cohort study in Southwest China. A total of 22,575 participants aged 40 years or older, recruited from four centers between April 2020 and June 2022, were included in the analysis. All participants had valid pre-bronchodilator spirometry results. Airflow obstruction was defined primarily as an FEV₁/FVC ratio below the Global Lung Function Initiative lower limit of normal. The prevalence of airflow obstruction was assessed and compared across subgroups. Risk factors were identified using univariate and multivariable logistic regression analyses. The overall prevalence of airflow obstruction was 14.9% (95% CI: 14.4–15.4), and 11.8% (95% CI: 11.3–12.3) among never smokers. Prevalence was significantly higher in men than in women (22.8% vs. 10.9%; P < 0.001) and increased progressively with smoking exposure (never smokers: 11.8%; former smokers: 19.7%; current smokers: 23.5%; P < 0.001). Among those with airflow obstruction, 91.3% presented with mild-to-moderate disease. Yet only 2.4% had been previously diagnosed with COPD. Multivariable analysis identified male sex, older age, smoking, biomass fuel exposure, lower body-mass index, lower education level, and sleep disturbance due to wheezing as significant factors independently associated with airflow obstruction. The high prevalence and pervasive underdiagnosis of airflow obstruction in Southwest China demand early detection and targeted prevention to reduce disease burden. This study has been registered with the Chinese Clinical Trial Registry ( No. ChiCTR1900024623), with the registration date of July 19, 2019. The trial registration was completed before the first participant was enrolled.