Comparison of lung function in 71 infants with cystic fibrosis and 54 healthy controls
| Variables according to test order | n | Infants with CF | n | Healthy controls | Δ (95% CI) CF – controls | p Values |
| Multiple breath washout | ||||||
| LCI, z-score* | 70 | 0.90 (1.38) | 51 | 0.39 (0.88) | 0.51 (0.10 to 0.91) | 0.016 |
| FRCMBW, z-score* | 70 | 0.15 (0.95) | 51 | −0.23 (0.86) | 0.38 (0.05 to 0.71) | 0.023 |
| Tidal breathing | ||||||
| Respiratory rate, z-score† | 71 | −0.01 (1.43) | 54 | 0.02 (1.21) | −0.03 (−0.50 to 0.44) | 0.897 |
| Tidal volume, z-score† | 71 | 0.20 (1.19) | 54 | −0.22 (1.09) | 0.42 (0.01 to 0.82) | 0.044 |
| tPTEF/tE, z-score† | 71 | 0.22 (1.05) | 54 | 0.41 (1.0) | −0.19 (−0.56 to 0.18) | 0.312 |
| Passive mechanics | ||||||
| Crs, z-score† | 47 | 0.22 (1.48) | 41 | 0.14 (0.96) | 0.08 (−0.44 to 0.60) | 0.763 |
| Rrs, z-score† | 47 | 0.52 (0.94) | 41 | 0.28 (1.04) | 0.24 (−0.18 to 0.66) | 0.237 |
| Plethysmography | ||||||
| FRCpleth, z-score† | 56 | 0.77 (1.15) | 47 | −0.08 (1.03) | 0.85 (0.43 to 1.28) | <0.001 |
| ΔFRC z-scores (pleth − MBW) | 55 | 0.68 (1.10) | 45 | 0.19 (0.92) | 0.48 (0.08 to 0.88) | 0.018 |
| Raised volume technique | ||||||
| FEV0.5, z-score‡ | 68 | −1.17 (1.20) | 52 | −0.25 (0.80) | −0.92 (−1.29 to −0.56) | <0.001 |
| FVC, z-score‡ | 68 | −0.45 (1.07) | 52 | 0.15 (0.71) | −0.60 (−0.92 to −0.28) | <0.001 |
| FEF25–75, z-score‡ | 68 | −1.11 (1.38) | 52 | −0.46 (1.08) | −0.66 (−1.10 to −0.21) | 0.004 |
| FEF75, z-score‡ | 68 | −0.74 (1.19) | 52 | −0.22 (1.11) | −0.53 (−0.95 to −0.11) | 0.015 |
For comparison with previous publications, results expressed as absolute values, or in relation to body weight, are presented in table E2, online supplement.
Data shown as mean (SD).
↵* According to Lum et al. 31
↵† According to Nguyen et al. 32
↵‡ According to Lum et al. 34
CF, cystic fibrosis; CI, confidence interval of the difference; Δ, mean difference between groups.
CF, cystic fibrosis; Crs, total respiratory compliance; FEF75, forced expiratory flow at 75% of vital capacity; FEF25-75, forced expiratory flow between 25% and 75% of vital capacity; FEV0.5, forced expiratory volume in 0.5 s; FRC, functional residual capacity; FVC, forced vital capacity; LCI, lung clearance index; MBW, multiple breath washout; pleth, plethysmographic; Rrs, total respiratory resistance; tPTEF/tE, ratio of the time to reach peak tidal expiratory flow in relation to expiratory time.