Table 4.
The proportion of people in excess of thresholds for overall cohort, for subgroups of normal, GOLD stage 1, GOLD stage 2 and GOLD stage 3–4
| Variables | Overall | Normal | GOLD stage 1 | GOLD stage 2 | GOLD stage 3–4 |
| FEV1-based thresholds | N1=10 217 | N1=7931 | N1=846 | N1=790 | N1=219 |
| ΔFEV1 (>284 ml) | 6.7% | 5.6% | 11.5% | 12.2% | 7.3% |
| ΔFEV1i (>12%) | 7.8% | 4.4% | 11.6% | 27.3% | 43.4% |
| ΔFEV1p (>10%) | 6.0% | 4.3% | 12.3% | 13.9% | 9.1% |
| FVC-based thresholds | N2=9546 | N2=7697 | N2=819 | N2=764 | N2=212 |
| ΔFVC (>322 ml) | 7.5% | 4.0% | 21.2% | 20.7% | 29.7% |
| ΔFVCi (>10.5%) | 7.5% | 3.8% | 17.0% | 24.7% | 42.5% |
| ΔFVCp (>9.2%) | 6.8% | 3.2% | 21.6% | 20.5% | 27.8% |
ΔFEV1 (ml) and ΔFVC (ml) are absolute change after bronchodilator; ΔFEV1i and ΔFVCi are change as a per cent of initial value; ΔFEV1p and ΔFVCp are change as per cent of predicted value. N1 is number with non-missing FEV1 values and N2 is number with non-missing FVC values.
Normal = not classified as any GOLD stage; GOLD stage 1 = FEV1/FVC <0.7 and FEV1 % predicted >80%; GOLD stage 2 = FEV1/FVC <0.7 and FEV1 % predicted <80% and >50%; GOLD stage 3–4 = FEV1/FVC <0.7 and FEV1 % predicted <50%.
COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease.