Chronic bronchitis and bronchitis-like symptom definitions
| Baseline (2006–2013) | |
| Prevalent outcomes | Assessment item |
| Chronic bronchitis | Cough up phlegm in winter when getting up, during daytime or at night almost daily for at least 3 months a year |
| Usual sputum | Usually cough up phlegm in winter when getting up, during daytime or at night |
| Chronic cough | Cough in winter when getting up, during daytime or at night almost daily for at least 3 months a year |
| Usual cough | Usually cough in winter when getting up, during daytime or at night |
| Follow up (2014–2017) | |
| Incident outcomes | Assessment item |
| Chronic bronchitis | Cough up mucus every day for a period of 3 months a year |
| Chronic cough | Cough almost every day for a period of 3 months a year |