Table 1.
Baseline characteristics of the study populations
| UK Smoking Cohort | Smoking Controls |
COPD Cases |
GOLD stage 3 and 4 | Comparison (smoking controls vs. COPD cases | Comparison (smoking controls vs. GOLD 3/4 | |
|---|---|---|---|---|---|---|
| Age | 63.33 ± 10.29 | 54.38 ± 9.52 | 65.96 ± 9.01 | 67.16 ± 8.56 | p < 0.0001 | p < 0.0001 |
| Female (%) | 43.8 | 56.3 | 39.9 | 38.8 | p = 0.037 | p = ns |
| Baseline FEV1 % predicted | 56.05 ± 28.16 | 96.03 ± 12.15 | 40.31 ± 15.63 | 31.46 ± 8.69 | p < 0.0001 | p < 0.0001 |
| FEV1/FVC Ratio | 55.34 ± 17.43 | 77.30 ± 5.90 | 46.3 ± 12.5 | 41.57 ± 11.20 | p < 0.0001 | p < 0.0001 |
| Post BD FEV1 % predicted | 59.08 ± 27.14 | 99.48 ± 11.72 | 44.65 ± 15.52 | 35.28 ± 8.90 | p = 0.049 | p < 0.0001 |
| PostBD FEV1/FVC Ratio | 55.58 ± 17.71 | 79.10 ± 5.05 | 46.2 ± 12.00 | 41.27 ± 10.46 | p < 0.0001 | p < 0.0001 |
| Pack Years | 43.54 ± 26.05 | 32.74 ± 20.04 | 47.61 ± 27.01 | 47.96 ± 27.85 | p < 0.0001 | p < 0.0001 |
| GOLD Stage (%): | ||||||
| • Stage 1 | 6.9 | 0.0 | 0.0 | 0.0 | ||
| • Stage 2 | 32.6 | 0.0 | 34.8 | 0.0 | ||
| • Stage 3 | 42.4 | 0.0 | 45.5 | 69.9 | ||
| • Stage 4 | 18.2 | 0.0 | 19.7 | 30.1 | ||
| Number | 992 | 176 | 599 | 389 | ||
FEV1, Forced expiratory volume in one second; FVC, forced vital capacity; BD, bronchodilator. Control subjects were defined as having postBD (salbutamol) FEV1 > 80% and postBD FEV1/FVC > 0.7. Subjects with COPD were defined as having postBD FEV1 < 80% and FEV1/FVC < 0.7. Individuals who did not meet these criteria were excluded from analyses. Continual variables between groups were compared by Independent T-Test, categorical variables by Pearson chi square.