Characteristics of groups used to train the reference equations

Age# years42±11.642±12.4
Height cm183±6.7170±6.4
Weight kg84±9.869±8.9
BMI kg·m−224.9±2.523.9±2.8
FEV1 L4.40±0.633.19±0.49
FEV1 % pred99±9.198±9.2
FVC L5.58±0.743.99±0.56
FVC % pred100±9.0101±9.4
FEF25 L·s−18.50±1.566.10±1.13
FEF25 % pred
FEF50 L·s−14.87±1.223.67±0.91
FEF50 % pred
FEF75 L·s−11.63±0.631.25±0.54
FEF75 % pred101±29.796±30.2
FEF25–75 L·s−14.03±1.103.03±0.86
FEF25–75 % pred96±22.392±20.5

Data are presented as n or mean±sd. Predicted values are according to the Global Lung Initiative (GLI) equations [13]. BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; FEFx: forced expiratory flow at 25%, 50%, 75% or 25–75% of FVC. #: age range (interquartile range) 18–80 (34–49) years and 18–85 (33–48) years for males and females, respectively; : no reference equations available from the GLI. For characteristics of internal and external validation sets see supplementary table S2.