Participant characteristics at baseline by exacerbation status during follow-up
| Variable | Exacerbation group | No exacerbation group | Exacerbation unknown | Comparison |
| Subjects n | 46 | 59 | 17 | NS |
| Female | 45.7% | 47.5% | 29.4% | NS |
| Age years | 67.2±7.2 | 68.5±7.3 | 64.3±7.4 | NS |
| Smoking status | NS | |||
| Daily | 19.6% | 27.1% | 23.5% | |
| Ex-smoker | 78.3% | 72.9% | 76.5% | |
| Never | 2.2% | 0% | 0% | |
| FEV1 % pred | 46.1±17.0 | 60.4±17.3 | 68.3±22.6 | p<0.01 |
| FEV1/FVC | 0.40±0.12 | 0.49±0.11 | 0.45±0.12 | p<0.01 |
| CAT-score# | 19.4±8.1 | 15.5±7.5 | 12.5±6.4 | p=0.01 |
| PaO2 kPa¶ | 9.4±1.2 | 9.8±1.2 | 9.6±1.2 | NS |
| Exacerbation ≥2 previous year | 32.6% | 10.2% | 5.9% | p<0.01 |
| Daily use of inhaled corticosteroids | 69.6% | 39.0% | 35.3% | p≤0.01 |
| Daily use of oral steroids | 6.5% | 3.4% | 5.9% | NS |
Data are presented as % or mean±sd, unless otherwise stated. The comparisons were between the exacerbation and no exacerbation groups only, and were tested using t-tests and Chi-squared tests. NS: not significant; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; CAT: COPD Assessment Test; PaO2: arterial oxygen tension. #: Two missing values; ¶: three missing values.