Incidence of acute exacerbation and its related factors among chronic obstructive pulmonary disease patients aged 40 years and older in China.

Background: Acute exacerbation of chronic obstructive pulmonary disease (COPD) (AECOPD) represents a pivotal event in the clinical course of COPD and contributes substantially to disease progression and healthcare burden. This study examined the incidence and demographic distribution of AECOPD among Chinese COPD patients aged ≥40 years and evaluated factors associated with its occurrence, providing population-based evidence to inform community prevention, standardized treatment, rehabilitation, and health management strategies. Methods: Data were derived from the Chinese Chronic Obstructive Pulmonary Disease Surveillance (2019-2020), a nationwide cross-sectional survey conducted in 125 surveillance counties (districts) across 31 provinces, autonomous regions, and municipalities in China. Using a multistage stratified cluster random sampling design, residents aged ≥40 years were enrolled. Participants completed standardized questionnaires, physical measurements, and pre- and post-bronchodilator spirometry administered by trained investigators. COPD was defined as a post-bronchodilator forced expiratory volume in one second (FEV₁)/forced vital capacity (FVC) <70%. The incidence of AECOPD and corresponding hospitalization rates were estimated and compared across subgroups. Stepwise multivariable logistic regression was used to identify factors associated with AECOPD, with Model I including sociodemographic, behavioral, and environmental factors and Model II additionally incorporating disease-related characteristics. Results: A total of 7455 COPD patients were included in the analysis. The overall incidence of AECOPD was 9.0% (95% confidence interval [CI]: 7.9-10.1%), and the hospitalization rate was 4.3% (95% CI: 3.5-5.0%). Higher incidence and hospitalization rates were observed among patients aged ≥65 years (10.8%, 5.7%) and those residing in southern region (10.3%, 5.0%). Elevated rates were also noted among individuals with body mass index (BMI) <18.5 kg/m² (16.1%, 10.0%), smoking history (9.1%, 4.3%), prior hospital admission for severe pulmonary disease in childhood (21.6%, 9.3%), exposure to biomass (10.8%, 5.3%), occupational exposure to harmful factors (10.5%, 4.9%), and a history of chronic respiratory diseases (28.2%, 14.9%). The highest rates were observed in patients with a modified Medical Research Council (mMRC) score ≥2 (40.7%, 23.0%). Rates were 22.4% and 11.5% among those with a COPD Assessment Test (CAT) score ≥10 and 33.0% and 19.5% among those with ≥3 comorbidities. By Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades, incidence and hospitalization rates were 4.6% and 1.7% (Stage I), 10.7% and 4.6% (Stage II), and 28.7% and 18.9% (Stages III-IV). Multivariable analyses identified residence in southern region, hospital admission for severe pulmonary disease in childhood, mMRC score ≥2, CAT score ≥10, GOLD stage III-IV, and a higher number of comorbidities as independent risk factors for AECOPD. Conclusion: AECOPD incidence and hospitalization rates remain substantial among community-dwelling COPD patients aged ≥40 years in China, with a significantly higher burden in southern region. Early-life severe respiratory disease, greater symptom severity, poorer lung function, and multiple comorbidities are strongly associated with increased AECOPD risk. Addressing regional disparities, strengthening comprehensive assessment and management, identifying high-risk individuals, and implementing targeted community-based interventions are essential to reduce AECOPD risk and mitigate the overall burden of COPD.