Baseline characteristics, lung function values and health status scores for the whole patient group, patients with and without exacerbations over the first year and for the group followed for 3 yrs
| All patients | Patients with no exacerbations over year 1 | Patients with ≥1 exacerbation over year 1 | p-value# | Subgroup studied for 3 yrs | |
| Subject n | 265 | 123 | 142 | 87 | |
| Age yrs | 49.9±0.6 | 50.0±1.0 | 49.9±0.8 | ns¶ | 50.2±1.0 |
| Body mass index kg·m−2 | 25.0 (22.9–27.8) | 25.1 (23.2–27.8) | 24.8 (22.2–27.8) | ns | 25.0 (23.0–27.0) |
| Smoking history pack-yrs | 13.0 (1.4–24.0) | 12.0 (0.5–22.8) | 14.6 (4.0–26.0) | ns | 17.5 (0–25.0) |
| Smoking status | |||||
| Current | 17 | 8 | 9 | ns+ | 0 |
| Ex | 187 | 84 | 103 | 65 | |
| Never | 61 | 31 | 30 | 22 | |
| Sex | |||||
| Male | 167 | 80 | 87 | ns+ | 59 |
| Female | 98 | 43 | 55 | 28 | |
| Presentation | |||||
| Index | 210 | 90 | 120 | 0.023+ | 67 |
| Non-index | 55 | 33 | 22 | 20 | |
| Chronic bronchitis | |||||
| Yes | 110 | 39 | 71 | 0.003+ | 35 |
| No | 155 | 84 | 71 | 52 | |
| Inhaled steroid use over initial 12 months | |||||
| Yes | 146 | 56 | 90 | 0.002+ | 47 |
| No | 106 | 64 | 42 | 37 | |
| Altered | 13 | 3 | 10 | 3 | |
| Bronchodilator reversibility | |||||
| Yes | 65 | 23 | 42 | 0.034+ | 23 |
| No | 198 | 100 | 98 | 63 | |
| FEV1 L | 1.53 (1.02–2.45) | 1.77 (1.11–2.93) | 1.42 (0.98–2.16) | 0.005 | |
| FEV1 % pred | 46.2 (33.8–76.8) | 55.2 (35.6–95.3) | 43.3 (32.9–68.5) | 0.013 | |
| VC L | 4.13 (3.16–4.99) | 4.28 (3.66–5.11) | 3.97 (2.85–4.92) | 0.049 | |
| VC % pred | 103.5 (91.4–117.3) | 106.9 (95.6–119.9) | 101.7 (87.6–115.9) | 0.044 | |
| RV L | 2.58 (2.04–3.24) | 2.51 (2.00–3.16) | 2.72 (2.18–3.42) | 0.037 | |
| RV % pred | 129.7 (102.6–155.1) | 126.1 (99.7–148.9) | 137.4 (106.7–173.8) | 0.008 | |
| TLC L | 7.40 (6.06–8.40) | 7.38 (6.20–8.54) | 7.47 (5.91–8.37) | ns | |
| TLC % pred | 119.0 (107.4–130.5) | 118.4 (107.7–128.1) | 119.1 (108.1–132.6) | ns | |
| RV/TLC % | 36.4 (29.4–43.0) | 34.3 (28.0–41.5) | 38.9 (32.4–45.5) | 0.002 | |
| TL,CO mmol·min−1·kPa−1 | 6.37 (4.65–8.27) | 6.60 (4.99–8.46) | 5.86 (4.29–7.85) | 0.035 | |
| TL,CO % pred | 68.0 (52.0–85.0) | 72.0 (55.0–88.0) | 63.6 (50.0–83.0) | 0.055 | |
| TL,CO/VA mmol·min−1·kPa−1·L−1 | 1.08 (0.80–1.39) | 1.12 (0.80–1.44) | 1.00 (0.78–1.35) | ns | |
| TL,CO/VA % pred | 67.9 (53.7–86.0) | 69.0 (55.0–87.0) | 66.2 (51.0–85.7) | ns | |
| SGRQ | |||||
| Total | 51.6 (31.5–65.3) | 45.3 (25.1–58.2) | 55.4 (38.0–68.7) | <0.001 | |
| Symptoms | 64.0 (44.1–78.8) | 57.7 (36.8–72.6) | 70.9 (53.6–83.8) | <0.001 | |
| Activity | 66.2 (41.4–85.9) | 59.5 (35.2–79.7) | 72.8 (48.5–92.6) | <0.001 | |
| Impacts | 36.8 (20.0–52.5) | 31.8 (14.7–46.3) | 41.5 (25.2–56.8) | <0.001 | |
| SF36 | |||||
| Physical | 37.7 (28.9–45.9) | 40.5 (32.6–49.7) | 34.0 (26.7–42.5) | <0.001 | |
| Mental | 53.2 (45.2–58.7) | 53.3 (46.4–58.8) | 53.1 (42.5–58.5) | ns |
Data are presented as mean±se or median (interquartile range), unless otherwise stated. ns: nonsignificant; FEV1: forced expiratory volume in one second; % pred: % predicted; VC: vital capacity; RV: residual volume; TLC: total lung capacity; TL,CO: gas transfer of the lung for carbon monoxide; VA: alveolar volume; SGRQ: St George's Respiratory Questionnaire; SF36: Short-Form 36. #: univariant comparison of those with and without exacerbations; ¶: t-test; +: Chi-squared test. All other statistical comparisons used the Mann-Whitney U-test.