There were a total of 29,319 survey respondents from 15,300 households. The response rate among adults in the selected villages was 90.1%. There were no significant differences in terms of demographic variables between respondents and those who did not take part in this survey. The final sample was representative of the municipality by age, gender, and residential area. Urban and rural residents consisted of 67.7% and 32.3%, respectively. Moreover, 49.7% were men and 50.3% were women. The demographic characteristics of the participants are shown in Tables 1 and 2. The average pack-years of cigarettes smoked was 7,688 for urban smokers and 9,671 for rural smokers. Male smokers consumed 8,477 cigarettes on average, while female smokers consumed 7,045 cigarettes on average.
COPD is one of the most common public health problems worldwide and is the fourth-leading cause of death in the world. It has been estimated that COPD will become the third-most-frequent cause of death and the fifth-most-common cause of disability by the year 2020. According to a comprehensive review, the overall prevalence of COPD ranges from < 1 to > 18% in different populations, and this variation is probably due to different methods used in the estimations. In mainland China, COPD is currently the second-leading cause of death. However, the only COPD prevalence available for mainland China is 2.5% overall, which was estimated based on World Health Organization (WHO) expert opinions. Instead of conducting population surveys, the WHO experts estimated the prevalence of COPD on the basis of published and unpublished studies. If the data were not available, experts would often make “informed estimates” based on the prevalence in similar countries or regions.