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

VariablesOverallNormalGOLD stage 1GOLD stage 2GOLD stage 3–4
FEV1-based thresholdsN1=10 217N1=7931N1=846N1=790N1=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 thresholdsN2=9546N2=7697N2=819N2=764N2=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.