CF subjects | Control subjects | Mean difference (95% CI)# | p-value | |
Subjects | 61 | 48 | ||
Males | 27 | 26 | NA | 0.459¶ |
Age yrs | 11.1±3.0 | 11.8±2.9 | 0.7 (-0.4–1.8) | 0.224 |
Height z-score | -0.57±1.20 | 0.16±1.03 | 0.72 (0.23–1.21) | 0.004 |
Weight z-score | -0.66±1.07 | -0.05±1.06 | 0.61 (0.16–1.10) | 0.009 |
Double-tracer gas SBW n | 61 | 48 | ||
SIIIDTG mg·mol·L−1 | -456.7±492.8 | -88.4±129.1 | 368.3 (237.1–499.5) | <0.001 |
SnIIIDTG mg·mol−1 | -181.2±177.8 | -57.1±85.9 | 124.1 (68.7–179.4) | <0.001 |
MBNW n | 51 | 44 | ||
LCI | 12.1±3.5 | 6.7±1.1 | 5.4 (4.3–6.5) | <0.001 |
Sacin | 0.23±0.16 | 0.07±0.06 | 0.16 (0.11–0.21) | <0.001 |
Scond | 0.07±0.07 | 0.04±0.06 | 0.03 (0.001–0.05) | 0.041 |
Spirometry n | 61 | |||
FEV1 z-score | -1.45±1.46 | NA | NA | |
FEF25–75% z-score | -1.86±1.59 | NA | NA |
Data are presented as n or mean±sd, unless otherwise stated. #: compared by unpaired t-tests giving mean difference with 95% confidence intervals; ¶: sex distribution was assessed by Fisher’s exact test. SBW: single-breath washout; SIIIDTG: double-tracer gas SBW-derived tidal phase III slope; SnIIIDTG: double-tracer gas SBW-derived tidal phase III slope normalized by tidal volume; MBNW: nitrogen multiple-breath washout; Scond: index of conductive ventilation inhomogeneity; Sacin: index of acinar ventilation inhomogeneity; NA: not applicable. z-scores for forced expiratory volume in 1 s (FEV1) and forced expiratory flow between 25%–75% of expired volume (FEF25–75%) were calculated from reference data [22].