Proportion of participants experiencing clinically relevant improvement, deterioration or no change in respiratory parameters between baseline and 1 year study visits, among those completing both visits (n=368), with median size of change shown for continuous variables.
| Parameter | Classification of change | Proportion of participants with each pattern of change (n, %)* Median (IQR) change observed | ||
| Improvement | No change | Deterioration | ||
| Self-reported general health | Change of ≥1 category in self-reported general health (poor, fair, good, excellent) | 115 (31.3%) | 229 (62.2%) | 24 (6.5%) |
| BMI (kg/m2) | Change ≥1.46 kg/m2† | 105 (28.5%) 2.7 (1.9 to 4.1) | 244 (66.3%) 0.2 kg/m2 (−0.2 to 0.8) | 19 (5.2%) −2.4 kg/m2 (−3.4 to −1.7) |
| SGRQ total score (n=366) | Change ≥4units‡ | 167 (45.6%) −16.1 points (−23.8 to −9.2) | 153 (41.8%) −0.4 points (−1.8 to 0) | 46 (12.6%) +11.5 points (7.0 to 25.9) |
| 6 min walking distance (m) (n=348) | Change ≥26 m‡ | 201 (57.8%) 70 m (46 to 105 m) | 102 (29.3%) 8 m (−4 to 15 m) | 45 (12.9%) −49 m (−65 to −38 m) |
| Presence of monthly respiratory symptoms | Change between present / absent monthly symptoms | 133 (36.1%) | 207 (56.3%) | 28 (7.6%) |
| FEV1 volume (L) (n=305) | Change ≥100 mL‡ | 133 (43.6%) 230 m (150 to 340) | 113 (37.1%) 0 mL (−40 to 40) | 59 (19.3%) −200 mL (−230 to −130) |
| FVC volume (L) (n=305) | Change ≥100 mL‡ | 164 (53.8%) 280 mL (190 to 400) | 98 (32.1%) 30 mL (−40 to 60) | 43 (14.1%) −160 mL (−220 to −120) |
| % abnormal parenchyma on CXR (n=359) | Change ≥4.68%† | 58 (16.2%) −8.3% (−12.1 to −6.3) | 283 (78.8%) 0% (−1.7 to 0.4) | 18 (5.0%) +7.9% (6.3 to 13.3) |
| Ring and tramline score (0–18) on CXR (n=359) | Change ≥1.17 points† | 79 (22.0%) −2.5 points (−4.0 to 2.0) | 218 (60.7%) 0 points (−0.5 to 0) | 62 (17.3%) 2.0 points (1.5 to 3.0) |
*Pattern of change over 1 year period, classified using ‘Minimally important clinical difference (MCID)’ cut-offs for continuous variables, and change in response category for ordinal variables. Improvement: Increase ≥MCID or improvement by ≥1 category; No change: Remaining within +/-MCID of baseline reading, or remaining in same category; Deterioration: Reduction ≥MCID or deterioration by ≥1 category.
†No existing MCID agreed in literature: cut-off calculated by 0.5 x SD of baseline data.
‡MCID derived from COPD literature.42
BMI, body mass index; CXR, chest radiography; SGRQ, St George’s Respiratory Questionnaire.