Baseline characteristics of the patients in the intention-to-treat population
| Total | Placebo | Theophylline plus placebo | Theophylline plus prednisone | |
| Patients | 1670 | 554 | 568 | 548 |
| Age years | 64.4±8.0 | 63.9±8.5 | 64.4±7.8 | 64.9±7.7 |
| Male | 1264 (75.7) | 426 (76.9) | 434 (76.4) | 404 (73.7) |
| BMI kg·m−2# | 22.3±3.5 | 22.4±3.5 | 22.3±3.5 | 22.3±3.5 |
| Smoking status# | ||||
| Current smoker | 332 (19.9) | 98 (17.7) | 121 (21.3) | 113 (20.6) |
| Ex-smoker | 889 (53.3) | 309 (55.8) | 299 (52.7) | 281 (51.3) |
| Never-smoker | 448 (26.8) | 147 (26.5) | 147 (25.9) | 154 (28.1) |
| Pack-years | ||||
| Current smoker | 42.7±23.9 | 43.5±27.1 | 40.5±22.3 | 44.4±22.7 |
| Ex-smoker | 38.2±20.8 | 39.3±22.7 | 38.5±19.8 | 36.7±19.6 |
| Spirometry | ||||
| Pre-BD FEV1 L | 1.0±0.4 | 1.0±0.4 | 1.0±0.4 | 0.9±0.4 |
| Post-BD¶ FEV1 L | 1.1±0.4 | 1.1±0.4 | 1.1±0.4 | 1.0±0.4 |
| Post-BD¶ FEV1 % pred | 42.2±15.8 | 42.1±15.5 | 43.0±15.8 | 41.6±15.9 |
| Post-BD¶ FEV1/FVC | 0.48 | 0.48 | 0.46 | 0.43 |
| GOLD severity of airflow limitation | ||||
| Mild | 22 (1.3) | 5 (0.9) | 12 (2.1) | 5 (0.9) |
| Moderate | 429 (25.8) | 146 (26.7) | 152 (26.8) | 131 (23.9) |
| Severe | 821 (49.4) | 265 (48.4) | 279 (49.2) | 277 (50.6) |
| Very severe | 389 (23.4) | 131 (23.9) | 124 (21.9) | 134 (24.5) |
| Prior year exacerbation rate+ | 0.7±1.0 | 0.7±1.1 | 0.7±1.0 | 0.7±1.1 |
| Dust and fume exposure# | 286 (17.1) | 97 (17.5) | 99 (17.5) | 90 (16.4) |
| Biomass exposure# | 641 (38.4) | 209 (37.7) | 214 (37.8) | 218 (39.8) |
| CAT score | 18.1±7.4 | 18.3±7.4 | 17.8±7.6 | 18.1±7.3 |
| SGRQ total score | 45.8±20.1 | 46.5±19.9 | 44.8±20.7 | 46.2±19.5 |
| Total white blood cells ×109 L−1# | 6.7±2.2 | 6.8±2.1 | 6.7±2.2 | 6.8±2.2 |
| Eosinophils ×109 L−1 | 0.3±0.6 | 0.3±0.7 | 0.3±0.7 | 0.3±0.5 |
Data are presented as n, mean±sd or n (%). BMI: body mass index; BD: bronchodilator; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; GOLD: Global Initiative for Chronic Obstructive Lung Disease; CAT: COPD Assessment Test; COPD: chronic obstructive pulmonary disease; SGRQ: St George's Respiratory Questionnaire. #: at screening (≤2 weeks from baseline); ¶: 15 min following 400 mg salbutamol; +: exacerbation defined as a worsening of respiratory symptoms necessitating the use of antibiotics, oral corticosteroids or both in the year prior to randomisation.