Characteristics of the population included in the study and univariate analysis of variables possibly associated with relapse
| Variable | Total population | Success | Relapse | p-value |
| Subjects n | 2414 | 1907 | 507 | |
| Males % | 74.2 | 74.8 | 74.1 | 0.785 |
| Age yrs | 67.1±10.3 | 66.9±10.1 | 68.1±10.2 | 0.022 |
| BMI kg·m−2 | 27.4±4.1 | 27.3±4.0 | 27.4±4.2 | 0.388 |
| Active smokers % | 20.1 | 19.9 | 20.7 | 0.207 |
| Pack-yrs | 41.7±27.0 | 40.7±26.7 | 43.1±25.8 | 0.139 |
| Exacerbations previous year | 3.0±2.2 | 2.9±2.2 | 3.4±2.1 | <0.0001 |
| Visits to the GP the previous year | 5.3±4.3 | 4.9±3.8 | 6.6±5.1 | <0.0001 |
| Evolution of the disease yrs | 12.6±8.2 | 12.3±8.1 | 13.9±8.5 | 0.0007 |
| CMH % | 40.9 | 40.0 | 44.1 | 0.095 |
| Hypertension % | 34.1 | 33.6 | 35.7 | 0.391 |
| Diabetes mellitus % | 14.2 | 13.5 | 15.9 | 0.153 |
| Ischaemic heart disease % | 8.5 | 7.1 | 11.8 | 0.002 |
| Exacerbation% | ||||
| type 1 | 49.1 | 48.4 | 51.8 | 0.262 |
| type 2 | 34.6 | 35.4 | 31.7 | |
| type 3 | 19.2 | 16.1 | 16.5 | |
| Dyspnoea % | ||||
| degree 0 | 9.0 | 10.0 | 5.4 | 0.001 |
| degree I | 40.2 | 42.4 | 31.9 | |
| degree II | 32.4 | 31.6 | 35.5 | |
| degree III | 14.5 | 13.4 | 18.5 | |
| degree IV | 3.8 | 2.5 | 8.6 |
Data are presented as absolute values or mean±sd
BMI: body mass index
GP: general practitioner
CMM: chronic mucus hypersecretion
Exacerbation types and dyspnoea degrees are defined in 9 and 8, respectively