Associations of chronic bronchitis symptoms with other respiratory symptoms, respiratory exacerbations and quality of life
| Total study sample | CAO+ | CAO− | |
| mMRC dyspnoea scale ≥2 | 1.54 (1.08–2.22) | 2.06 (1.01–4.22) | 1.63 (1.06–2.74) |
| Respiratory exacerbations | |||
| Breathing problems interfering with daily activities or causing subject to miss work in the previous year | 4.28 (3.07–5.95) | 5.66 (3.08–10.41) | 3.66 (2.41–5.55) |
| Breathing problems causing subject to see a healthcare provider in the previous year | 4.93 (3.28–7.41) | 3.93 (2.00–7.72) | 5.21 (3.06–8.88) |
| Hospitalisation for breathing problems in the previous year | 4.86 (2.67–8.82) | 4.54 (1.98–10.44) | 4.18 (1.65–10.59) |
| Quality of life | |||
| SF-12 mental score (lowest quartile) | 2.06 (1.52–2.77) | 4.04 (2.30–7.08) | 1.59 (1.10–2.30) |
| SF-12 physical score (lowest quartile) | 4.00 (2.89–5.53) | 5.43 (2.88–10.26) | 3.34 (2.26–4.95) |
Data are presented as OR (95% CI). Results adjusted for study site, age, sex, education, smoking status and exposure to passive smoke, occupational exposures to dust and fumes, biomass fuels use, asthma, tuberculosis, lung cancer, heart disease, chronic airway obstruction (CAO) (in the total study sample) and forced vital capacity, plus data on hypertension, diabetes and stroke in the analysis of the quality of life. mMRC: modified Medical Research Council; SF-12: 12-item Short Form Health Survey.