Table 3

Changes over time for spirometric z-scores from linear mixed models, contrasting preterm and control groups

Change between 8 and 18 years
VariablePretermControlsInteraction
zFEV1 −0.11 (−0.22 to −0.02) p=0.054−0.15 (−0.28 to −0.02) p=0.0220.04 (−0.13 to 0.21) p=0.66
zFVC0.39 (0.27 to 0.52) p<0.0010.13 (−0.01 to 0.27) p=0.060.26 (0.07 to 0.45) p=0.006
zFEV1/FVC−0.94 (−1.12 to −0.72) p<0.001−0.67 (−0.87 to −0.47) p<0.001−0.27 (−0.54 to −0.01) p=0.042
zFEF25%–75% −0.06 (−0.20 to 0.07) p=0.390.18 (0.04 to 0.31) p=0.014−0.23 (−0.42 to −0.04) p=0.016
zFEF75% −0.33 (−0.47 to −0.19) p<0.0010.02 (−0.14 to 0.17) p=0.84−0.35 (−0.56 to −0.13) p=0.002
  • Values are mean difference (95% CI), unless otherwise stated.

  • FEF25%–75%, forced expiratory flow at 25%–75% of FVC; FEF75%, forced expiratory flow at 75% of FVC expired.