ABSTRACT
<p><b>OBJECTIVE</b>To explore the methodology on prevalence study of chronic obstructive pulmonary disease (COPD) in line with the world, to obtain accurate epidemic data of COPD in China.</p><p><b>METHODS</b>A national multi-center cross-sectional survey on prevalence, risk factors and burden of COPD was conducted in China. In each area, a population-based cluster sample of approximately 1450 individuals aged 40 years or older was interviewed, using standardized questionnaires that were revised on the methodology of burden of lung diseases (BOLD) study and according under the context of China. All participants were submitted to pre-bronchodilator spirometry. Those with airflow limitation received post-bronchodilator spirometry, physical examination, X-rays of chest and EKG (electrocardiogram) tests. The post-bronchodialators FEV1/FVC < 70% was identified as having COPD.</p><p><b>RESULTS</b>Investigation has been completed with the same standardized procedures by all sites, up to the requirement of quality control. Over 85.0% of the spirometry tests and 95.0% of questionnaires had met the criteria of quality control in each area. Overall, 95.2% of the data was valid with acceptable spirometry and questionaire, and the valid response rate was 79.0%.</p><p><b>CONCLUSION</b>The protocol was in line with the international standards, by which the prevalence of COPD in China was of adequate quality and valid.</p>