Control of chronic obstructive pulmonary disease in urban populations: findings from a cross-sectional prevalence survey in Shenzhen, China

The prevalence of chronic obstructive pulmonary disease (COPD) among urban populations is generally lower than rural residents, but the disease burden is still high. We conducted a cross-sectional prevalence survey of COPD among residents aged ≥40 years in an emerging city Shenzhen, China from September 2018 to June 2019. Through multi-stage stratified random sampling, a total of 4157 eligible participants were invited to complete a questionnaire and to take the spirometry test; 3591 with available data were enrolled in the final analysis. Individuals were diagnosed with COPD if the post-bronchodilator FEV1/FVC ratio was less than 0.7. The estimated standardized prevalence of COPD among residents over 40 years old in Shenzhen was 5.92% (95% confidential intervals [CI] 4.05–8.34). Risk factors for COPD included elder age (adjusted odds ratio 1.206, 95% CI 1.120–1.299 per 10-year increase), smoking over 20 pack-years (1.968, 1.367–2.832), history of chronic bronchitis (1.733, 1.036–2.900) or asthma (4.920, 2.425–9.982), and exposure to higher annual minimum concentrations of ambient SO2 (1.156, 1.053–1.270 per 1-μg/m3 increase). Among 280 spirometry-diagnosed patients, most (221, 78.93%) patients were classified as mild COPD (GOLD stage I). This survey found that the prevalence of COPD in Shenzhen is low and most patients had mild symptoms, thus recommended screening using spirometry in primary health care to detect early-stage COPD. Increased risk from the exposure to air pollutants also indicated the urgent need for environmental improvement in city settings.