Table 3 Lung function results compared by diagnosis.
| Cystic fibrosis (n = 39) | Healthy controls (n = 21) | Mean (95% CI) difference* | p Value | |
|---|---|---|---|---|
| Respiratory rate (per min) | 38.2 (9.7) | 32.0 (5.2) | 6.2 (2.3 to 10.0) | 0.009 |
| Respiratory rate (Z score)† | 0.8 (1.4) | –0.3 (0.9) | 1.1 (0.4 to 1.8) | 0.002 |
| Tidal volume (ml) | 70.3 (24.2) | 71.3 (14.3) | –1 (–12.5 to 10.6) | 0.865 |
| Minute ventilation (ml/min) | 2524 (543) | 2235 (374) | 287 (22 to 554) | 0.035 |
| FRCMBW (ml) | 170 (54) | 156 (38) | 14 (–13 to 41) | 0.295 |
| FRCMBW (Z score)‡ | –0.27 (1.0) | –1 (0.9) | 0.7 (0.3 to 1.2) | 0.004 |
| LCI | 8.4 (1.5) | 7.2 (0.3) | 1.2 (0.7 to 1.7) | <0.001 |
| FEV0.5 (Z score) | –1.6 (1.4) | 0.1 (0.9) | –1.7 (–2.3 to –1.1) | <0.001 |
| FVC (Z score) | –1.2 (1) | –0.1 (0.8) | –1.1 (–1.6 to –0.6) | <0.001 |
| FEF75 (Z score) | –1.8 (1.5) | –0.3 (0.9) | –1.4 (–2.1 to –0.8) | <0.001 |
| FEF25–75 (Z score) | –1.9 (1.5) | –0.4 (1) | –1.5 (–2.2 to –0.9) | <0.001 |
| FEV0.5/FVC (Z score) | –0.43 (1.26) | 0.27 (0.81) | –0.70 (–1.23 to –1.16) | 0.011 |
FEF, mid‐expiratory flow; FEV, forced expiratory volume; FVC, forced vital capacity; LCI, lung clearance index; FRC, functional residual capacity.
FRCMBW corrected for equipment and mask deadspace.
Results are expressed as mean (SD) unless specified otherwise.
*Difference calculated as cystic fibrosis−control.
†According to prediction equation by Ranganathan et al.27
‡According to the prediction equations for He dilution by Stocks and Quanjer.24