Elsevier

The Lancet

Volume 391, Issue 10131, 28 April–4 May 2018, Pages 1706-1717
The Lancet

Articles
Prevalence and risk factors of chronic obstructive pulmonary disease in China (the China Pulmonary Health [CPH] study): a national cross-sectional study

https://doi.org/10.1016/S0140-6736(18)30841-9Get rights and content

Summary

Background

Although exposure to cigarette smoking and air pollution is common, the current prevalence of chronic obstructive pulmonary disease (COPD) is unknown in the Chinese adult population. We conducted the China Pulmonary Health (CPH) study to assess the prevalence and risk factors of COPD in China.

Methods

The CPH study is a cross-sectional study in a nationally representative sample of adults aged 20 years or older from ten provinces, autonomous regions, and municipalities in mainland China. All participants underwent a post-bronchodilator pulmonary function test. COPD was diagnosed according to 2017 Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria.

Findings

Between June, 2012, and May, 2015, 57 779 individuals were invited to participate, of whom 50 991 (21 446 men and 29 545 women) had reliable post-bronchodilator results and were included in the final analysis. The overall prevalence of spirometry-defined COPD was 8·6% (95% CI 7·5–9·9), accounting for 99·9 (95% CI 76·3–135·7) million people with COPD in China. Prevalence was higher in men (11·9%, 95% CI 10·2–13·8) than in women (5·4%, 4·6–6·2; p<0·0001 for sex difference) and in people aged 40 years or older (13·7%, 12·1–15·5) than in those aged 20–39 years (2·1%, 1·4–3·2; p<0·0001 for age difference). Only 12·0% (95% CI 8·1–17·4) of people with COPD reported a previous pulmonary function test. Risk factors for COPD included smoking exposure of 20 pack-years or more (odds ratio [OR] 1·95, 95% CI 1·53–2·47), exposure to annual mean particulate matter with a diameter less than 2·5 μm of 50–74 μg/m3 (1·85, 1·23–2·77) or 75 μg/m3 or higher (2·00, 1·36–2·92), underweight (body-mass index <18·5 kg/m2; 1·43, 1·03–1·97), sometimes childhood chronic cough (1·48, 1·14–1·93) or frequent cough (2·57, 2·01–3·29), and parental history of respiratory diseases (1·40, 1·23–1·60). A lower risk of COPD was associated with middle or high school education (OR 0·76, 95% CI 0·64–0·90) and college or higher education (0·47, 0·33–0·66).

Interpretation

Spirometry-defined COPD is highly prevalent in the Chinese adult population. Cigarette smoking, ambient air pollution, underweight, childhood chronic cough, parental history of respiratory diseases, and low education are major risk factors for COPD. Prevention and early detection of COPD using spirometry should be a public health priority in China to reduce COPD-related morbidity and mortality.

Funding

Ministry of Health and Ministry of Science and Technology of China.

Introduction

Chronic obstructive pulmonary disease (COPD) is a worldwide public health challenge because of its high prevalence and related disability and mortality.1, 2, 3, 4 The Global Burden of Disease study estimated that 174·5 million adults worldwide had prevalent COPD in 2015.1, 2 If spirometry-defined COPD is included, the disease burden could be as high as 384 million.3 3·2 million deaths were estimated to be due to COPD globally in 2015.4 In China, COPD was the third leading cause of death and accounted for more than 0·9 million deaths in 2013.5

The most recent Chinese national survey of COPD was done during 2002–04 among 20 245 adults aged 40 years or older and reported an overall prevalence of 8·2% (12·4% in men and 5·1% in women).6 Over the past decade, ambient air pollution has become a major public health crisis in China.7, 8 Moreover, the prevalence of cigarette smoking remains high in Chinese men.9 Assessment of the current burden of COPD in the general Chinese population is essential for the development of public health policy and rational planning of health-care resources. Furthermore, findings of a study indicated that COPD is becoming more prevalent among young adults.10 However, no national data are available for COPD prevalence in adults younger than 40 years in China.

Research in context

Evidence before this study

We searched PubMed and the China National Knowledge Infrastructure for articles published up to December, 2017, using the terms “chronic obstructive pulmonary disease” or “COPD” and “prevalence” and “China”. We screened papers by reviewing abstracts to identify full-text reports that were relevant to the study aims. The most recent national survey of chronic obstructive pulmonary disease (COPD) in China was done during 2002–04 among 20 245 adults aged 40 years or older and reported an overall prevalence of 8·2% (12·4% in men and 5·1% in women). To the best of our knowledge, no national data for COPD prevalence in Chinese adults younger than 40 years are available.

Added value of this study

Our large, national, cross-sectional study was undertaken in a nationally representative sample of 50 991 adults from the general Chinese population. A post-bronchodilator pulmonary function test was done in all participants to diagnose COPD. Our findings indicate that, in 2015, the spirometry-defined prevalence of COPD was 8·6%, accounting for 99·9 million Chinese adults aged 20 years or older. The prevalence was 13·7% among people aged 40 years or older. For the first time, the prevalence of COPD was reported among the general population aged 20–39 years in China (2·1%). Additionally, our we showed that most people with COPD were unaware of their condition and few had received a previous pulmonary function test. Finally, cigarette smoking and heavy exposure to particulate matter with a diameter less than 2·5 μm were identified as major preventable risk factors for COPD in the Chinese adult population.

Implications of all the available evidence

Spirometry-defined COPD is highly prevalent and increasing in the Chinese adult population. Furthermore, the proportions of people with COPD who are aware of their condition or who have received pulmonary function tests are very low. Moreover, cigarette smoking and air pollution are major preventable risk factors for COPD. Our study calls for new national policy and programmes for the prevention and early detection of COPD. Specifically, health promotion for smoking cessation, control of ambient air pollution and biomass use, and screening for COPD using spirometry in high-risk individuals should be public health priorities.

In the China Pulmonary Health (CPH) study, we aimed to estimate the prevalence and absolute burden of COPD in the general Chinese population aged 20 years or older. Furthermore, we gathered and assessed risk factors for prevalent COPD and its awareness.

Section snippets

Study participants

We used a multistage stratified cluster sampling procedure to enrol a nationally representative sample of adults aged 20 years or older (appendix). In stage one, we selected ten provinces, autonomous regions, and municipalities stratified by geographical regions (only regions below an altitude of 1500 m were included). In stage two, we selected at random (using random numbers generated by SAS software) from each province or autonomous region a large city, a midsize city, an economically

Results

Between June, 2012, and May, 2015, 57 779 individuals (24 160 men and 33 619 women) were selected and invited to participate in the survey. 53 546 people (22 502 men and 31 044 women) completed the study (figure 1). The overall response rate was 92·7% (93·1% in men and 92·3% in women). After excluding individuals with unreliable post-bronchodilator tests, 50 991 participants (21 446 men and 29 545 women) were included in the final analysis. General characteristics and risk factors of the study

Discussion

To the best of our knowledge, our study is the largest survey of COPD in a nationally representative sample of the general Chinese adult population aged 20 years and older, and our findings fill several knowledge gaps about the COPD epidemic in China. First, our data indicate that 8·6% of the general Chinese adult population (or 99·9 million Chinese adults) aged 20 years or older in 2015 had spirometry-defined COPD, reaching epidemic proportions. Second, for the first time, the prevalence of

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