Table 5

Spirometry parameters according to different recommended classifications of airflow limitation severity

MildCOPD-X (n=35)GOLD (n=5)GLI-2012 (n=16)P value
FVC post-BD (L)2.98 (2.72, 3.24)4.08 (2.67, 5.48)3.5 (2.96, 4.03)0.034*
FVC post-BD (%)79.51 (74.24, 84.79)107.8 (88.78, 126.82)93.19 (85.31, 101.06)0.003*
FVC post-BD (z)−1.09 (−1.31, –0.86)1.18 (−0.28, 2.64)0.07 (−0.52, 0.66)<0.001*
FEV1 post-BD (L)1.94 (1.77, 2.12)2.76 (1.86, 3.66)2.32 (1.94, 2.69)0.024*
FEV1 post-BD (%)67.63 (65.77, 69.49)92.6 (77.53, 107.67)78.63 (71.78, 85.47)<0.001*
FEV1 post-BD (z)−2.06 (−2.24, –1.88)−0.23 (−1.18, 0.73)−1.17 (−1.59, –0.75)<0.001*
FEV1/FVC post-BD (AV)0.64 (0.62, 0.66)0.68 (0.65, 0.7)0.64 (0.61, 0.68)0.644
FEV1/FVC post-BD (%)83 (80.48, 85.52)85.6 (79.29, 91.91)84.38 (80.51, 88.24)0.479
FEV1/FVC post-BD (z)−2.34 (−2.57, –2.1)−1.91 (−2.53, –1.29)−2.3 (−2.62, –1.98)0.737
ModerateCOPD-X (n=96)GOLD (n=78)GLI-2012 (n=43)
FVC post-BD (L)2.3 (2.16, 2.43)2.75 (2.58, 2.91)2.61 (2.39, 2.83)0.002
FVC post-BD (%)62.61 (60.67, 64.56)72.97 (70.01, 75.94)73.49 (70.64, 76.34)<0.001*
FVC post-BD (z)−2.54 (−2.69, –2.38)−1.66 (−1.84, –1.47)−1.66 (−1.81, –1.5)<0.001*
FEV1 post-BD (L)1.4 (1.31, 1.48)1.75 (1.64, 1.85)1.66 (1.5, 1.82)<0.001*
FEV1 post-BD (%)48.46 (47.39, 49.53)59.83 (57.99, 61.68)59.12 (56.79, 61.44)<0.001*
FEV1 post-BD (z)−3.32 (−3.42, –3.21)−2.57 (−2.72, –2.43)−2.54 (−2.64, –2.45)<0.001*
FEV1/FVC post-BD (AV)0.61 (0.59, 0.62)0.63 (0.62, 0.64)0.62 (0.6, 0.65)0.111
FEV1/FVC post-BD (%)76.91 (74.37, 79.44)80.23 (77.46, 83.01)80.47 (78.04, 82.89)0.054
FEV1/FVC post-BD (z)−2.68 (−2.85, –2.5)−2.43 (−2.59, –2.27)−2.43 (−2.63, –2.23)0.042*
SevereCOPD-X (n=102)GOLD (n=97)GLI-2012 (n=83)
FVC post-BD (L)1.74 (1.64, 1.83)2.03 (1.92, 2.14)2.31 (2.16, 2.45)<0.001*
FVC post-BD (%)45.95 (43.79, 48.11)55.8 (53.96, 57.65)60 (57.39, 62.61)<0.001*
FVC post-BD (z)−4.06 (−4.26, –3.86)−3.14 (−3.31, –2.98)−2.71 (−2.86, –2.56)<0.001*
FEV1 post-BD (L)0.85 (0.8, 0.9)1.15 (1.08, 1.21)1.37 (1.28, 1.47)<0.001*
FEV1 post-BD (%)28.27 (26.87, 29.68)39.99 (38.86, 41.12)45.1 (43.13, 47.06)<0.001*
FEV1 post-BD (z)−4.67 (−4.8, –4.54)−3.87 (−3.98, –3.75)−3.49 (−3.56, –3.42)<0.001*
FEV1/FVC post-BD (AV)0.5 (0.48, 0.52)0.57 (0.55, 0.59)0.59 (0.58, 0.61)<0.001*
FEV1/FVC post-BD (%)61.85 (59.28, 64.43)72.38 (70.21, 74.55)73.72 (70.41, 77.04)<0.001*
FEV1/FVC post-BD (z)−3.95 (−4.13, –3.78)−3.13 (−3.32, –2.95)−2.88 (−3.05, –2.71)<0.001*
Very severeCOPD-XGOLD (n=58)GLI-2012 (n=96)
FVC post-BD (L)1.57 (1.45, 1.68)1.75 (1.65, 1.85)0.024*
FVC post- BD (%)40.97 (38.29, 43.64)46.79 (44.59, 48.99)0.001*
FVC post-BD (z)−4.51 (−4.75, –4.27)−4.19 (−4.38, –4.01)0.040*
FEV1 post-BD (L)0.72 (0.66, 0.77)0.89 (0.82, 0.96)<0.001*
FEV1 post-BD (%)23.4 (22, 24.79)29.41 (27.73, 31.09)<0.001*
FEV1 post-BD (z)−5.02 (−5.16, –4.88)−4.8 (−4.91, –4.69)0.015*
FEV1/FVC post-BD (AV)0.47 (0.44, 0.49)0.51 (0.49, 0.53)0.012*
FEV1/FVC post-BD (%)57.21 (53.66, 60.75)63.11 (60.56, 65.67)0.007*
FEV1/FVC post-BD (z)−4.28 (−4.5, –4.06)−3.94 (−4.14, –3.74)0.027*
  • *Statistically significant.

  • AV, absolute value; BD, bronchodilator; COPD, chronic obstructive pulmonary disease; COPD-X, concise tool for chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GLI, global lung initiative; GOLD, global initiative for chronic obstructive lung disease; Z, z-score.