TABLE 1.
Demographics of children with cystic fibrosis (CF) and healthy children for all visits with two or more acceptable multiple-breath washout (MBW) trials, visits with three or more acceptable MBW trials and visits with only two acceptable MBW trials obtained within a single testing session
| All visits (two or more acceptable trials) | Three or more acceptable trials | Two acceptable trials | ||||
| CF | Healthy | CF | Healthy | CF | Healthy | |
| Subjects | 71 | 47 | 49 | 36 | 22 | 11 |
| Test occasions | 104 | 61 | 66 | 42 | 38 | 19 |
| Age years | 5.1±1.0 | 4.8±1.1 | 5.0±1.0 | 4.8±1.1 | 5.1±1.0 | 5.0±0.8 |
| Male | 31 (44) | 22 (54) | 27 (43) | 19 (53) | 15 (39) | 6 (55) |
| Height cm | 109.9±8.8 | 108.8±8.2 | 109.7±8.8 | 108.8±8.2 | 108.4±8.9 | 111.1±7.1 |
| Weight kg | 19.4±3.7 | 19.2±3.9 | 19.7±3.8 | 19.2±3.9 | 18.9±3.5 | 21.0±5.1 |
| Height z-score | −0.08±1.0 | 0.17±1.0 | 0.04±1.1 | 0.09±1.1 | −0.27±0.95 | 0.34±0.95 |
| Weight z-score | 0.32±0.89 | 0.51±1.2 | 0.44±0.93 | 0.34±1.0 | 0.12±0.78 | 0.84±1.5 |
| Multiple-breath washout test | ||||||
| Functional residual capacity L | 0.88±0.23 | 0.85±0.18 | 0.87±0.25 | 0.87±0.17 | 0.89±0.21 | 0.94±0.17 |
| Lung clearance index | 8.13±1.54 | 7.10±0.60*** | 8.19±1.50 | 6.84±0.63*** | 8.05±1.66 | 6.69±0.48*** |
| First moment ratio | 1.78±0.31 | 1.65±0.12*** | 1.81±0.31 | 1.58±0.14*** | 1.75±0.32 | 1.52±0.10** |
| Second moment ratio | 6.91±2.79 | 5.54±0.87*** | 7.11±2.83 | 5.07±0.97*** | 6.63±2.82 | 4.62±0.59** |
| Respiratory infection | ||||||
| Any infection | 47/97 (48) | 24/60 (40) | 23/37 (62)* | |||
| Infection with a pro-inflammatory pathogen | 32/97 (33) | 17/60 (28) | 15/38 (39) | |||
| Inflammation | ||||||
| Total cell count ×106 mL−1 | 8.13±14.0 | 8.93±17.2 | 6.32±5.16 | |||
| Macrophages % | 75.1±23.4 | 76.2±23.1 | 79.8±18.3 | |||
| Neutrophils % | 23.3±23.0 | 23.0±23.1 | 19.3±18.8 | |||
| Neutrophil elastase present | 32/92 (35) | 18/55 (33) | 14/37 (38) | |||
| Neutrophil elastase ng·mL−1 | 874.4±2155.0 | 904.7±2067.6 | 1231.1±3127.9 | |||
| Interleukin-8 pg·mL−1 | 3227.34±7826.1 | 4228.2±9674.7 | 1454.7±2118.0 | |||
| Structural lung disease | ||||||
| Bronchiectasis present | 46/65 (71) | 33/49 (67) | 13/16 (81) | |||
| Bronchiectasis extent % | 1.25±2.89 | 1.11±2.51 | 1.67±4.09 | |||
| Air trapping present | 52/65 (80) | 35/49 (71) | 13/16 (81) | |||
| Air trapping extent % | 5.10±10.1 | 4.65±8.04 | 6.14±15.5 | |||
| Structural lung disease extent % | 4.04±3.56 | 3.96±2.69 | 3.91±5.68 | |||
Data are presented as n, mean±sd, n (%) or n/N (%). z-scores for height and weight were calculated using World Health Organization Child Growth Standards [16, 17]. Demographics and MBW outcomes were compared between children with CF and healthy children; MBW outcomes, demographics and clinical data were compared between visits with three or more acceptable trials and visits with only two acceptable trials. *: p<0.05; **: p<0.01; ***: p<0.001.