Prevalence and risk factors of small airway dysfunction among rural residents in Western China: a real-world cross-sectional study

Small airway dysfunction (SAD) is an early precursor to chronic obstructive pulmonary disease (COPD) and asthma but underdiagnosed, especially in rural settings. We aimed to estimate SAD prevalence and identify its risk factors among adults ≥ 40 years in rural western China. A cross-sectional survey was conducted among 11,398 rural residents aged ≥ 40 years in Mianyang, Sichuan, China. SAD was defined spirometrically as at least two of three indices below 65% of predicted values, including maximal mid-expiratory flow, forced expiratory flow at 50 and 75% of forced vital capacity. Multivariable logistic regression was used. Model 1 adjusted for age and sex; Model 2 additionally adjusted for education, smoking, household fuel use, residential dust exposure, and so forth. SAD prevalence was 49.21%. Higher risk was observed in older adults (≥60 years) and women (Model 2 OR = 1.74 [1.54–1.96]). Biomass fuel exposure (Model 1 OR = 1.29 [1.15–1.45]; Model 2 OR = 1.23 [1.07–1.41]) and coal fuel exposure (Model 1 OR = 1.23 [1.14–1.32]) were associated with SAD. Higher education and low residential dust exposure were protective. Subgroup analysis performed that in women, SAD prevalence increased with biomass fuel and secondhand smoke exposure. SAD is highly prevalent among rural adults aged ≥ 40 years in western China and is linked to multiple modifiable factors, particularly household solid fuel use. These findings suggest that routine pulmonary function screening in high-risk populations and targeted interventions, such as cleaner household energy, improved ventilation, and stratified health education, may contribute to early prevention of COPD and asthma.