Correlation coefficients (r) and significant levels (p) between mean individual ages and annual individual changes of forced expiratory volume in one second (FEV_{1}) or forced vital capacity (FVC) in 52 cystic fibrosis patients

Change of FEV_{1}

Change of FVC

r

p

r

p

% pred Z

0.40

0.003

0.31

0.03

% pred K

0.30

0.03

0.05

NS

% pred Q

0.09

NS

0.11

NS

% pred W

0.09

NS

0.19

NS

Z: using reference equation described in Zapletal et al.9

K: using reference equation described in Knudson et al.8

Q: using reference equation described in Quanjer et al.4

W: using reference equation described in Wang et al.6