Smoking and chronic obstructive pulmonary disease in Chinese population: a meta-analysis

In recent years, some epidemiological surveys of risk factors for chronic obstructive pulmonary disease (COPD) have been done in some regions of China, but the relevance is shown different in these surveys. A meta-analysis was undertaken to assess the relationship between smoking and COPD in Chinese population.

Twenty-four papers were included in our study. Total number of ever smokers and never smokers were 34,191 and 58,854, the number of COPD cases in each group were 5843 and 4874, respectively. We used meta-analysis method to analyze the selected papers quantitatively, and stratified by type of study, gender and smoking index.

Risk of COPD for ever smokers is higher than never smokers [odds ratio (OR) 2.90, 95% confidence interval (CI) 2.22 ∼ 3.80]; after stratifying by gender and smoking index, risks of COPD for male and female ever smokers are higher than male and female never smokers (OR 1.93, 95%CI 1.35 ∼ 2.77; OR 2.67, 95%CI 2.01 ∼ 3.56, respectively); risks of COPD for ever smokers who belong to different smoking index group (1 ∼ 200, 200 ∼ 400, >400, <300, ≥300 cigarettes per day*year) are all higher than never smokers (OR 2.49, 95%CI 1.66 ∼ 3.74; OR 2.91, 95%CI 2.19 ∼ 3.87; OR 4.07, 95%CI 3.17 ∼ 5.23; OR 2.39, 95%CI 1.42 ∼ 4.02; OR 3.31, 95%CI 2.99 ∼ 3.66, respectively).

The risk of COPD is higher for ever smokers than never smokers in Chinese population. The risk of COPD is higher for female smokers than male smokers. The risk of COPD is higher with greater smoking index.