| Operational diagnostic criteria of COPD |
| Data on COPD |
| Lung function |
| Respiratory symptoms |
| Biomarkers |
| Phenotypes of COPD |
| What actual and potential risk factors for COPD should be considered and how? |
| Active smoking |
| Occupational airborne exposure |
| Outdoor and indoor air pollution |
| Socioeconomic status |
| Diet |
| Comorbidity |
| Family history |
| Practical advice for planning and performing an epidemiological study on COPD |
| Population sampling and sample size |
| Ensuring a high response rate |
| The preparatory phase |
| The study team |
| Methods for data collection |
| The pilot study |
| Quality control |
COPD: chronic obstructive pulmonary disease.