Figure 1From: Impact of chronic obstructive pulmonary disease (COPD) in the Asia-Pacific region: the EPIC Asia population-based surveySampling strategy and response rate for the EPIC Asia survey. ‘Study subjects’ refers to the subset of individuals aged ≥40 years who were identified as having COPD, based on the definitions used in this study (see Methods), and who completed the questionnaire.Back to article page