Table 3.
MBW and spirometry parameters in children with PCD, children with CF, and healthy control children*
| Parameters | Subjects with PCD (n = 17) | Subjects with CF (n = 36) | HC Subjects (n = 53) | Pairwise Comparison P Values† |
||||
|---|---|---|---|---|---|---|---|---|
| PCD vs. HC | CF vs. HC | CF vs. PCD | ||||||
| MBW parameters | ||||||||
| LCI 2.5‡, median (IQR) | 8.19 (7.35 to 11.38) | 8.24 (7.30 to 9.68) | 6.94 (6.61 to 7.20) | <0.001 |
<0.001 |
0.85 |
||
| Abnormal LCI 2.5§, n (%) | 10 (59) | 21 (58) | 4 (8) | |
|
|||
| Spirometry | ||||||||
| FVC z-score‖, median (IQR) | 0.05 (−0.37 to 0.67) | −0.05 (−0.59 to 0.50) | 0.39 (−0.11 to 0.89) | 0.46 |
0.03 |
0.80 | ||
| FVC % predicted‖, median (IQR) | 101 (95 to 108) | 99 (93 to 106) | 105 (99 to 112) | 0.49 |
0.03 |
0.79 | ||
| Abnormal FVC§, n (%) | 2 (12) | 3 (8.3) | 0 (0.0) | |
|
|||
| FEV1z-score§, median (IQR) | −0.62 (−1.57 to −0.17) | −0.38 (−1.21 to 0.17) | 0.25 (−0.38 to 0.73) |
0.01 |
0.003 |
0.73 | ||
| FEV1% predicted‖, median (IQR) | 92 (82 to 98) | 96 (85 to 102) | 103 (95 to 109) |
0.007 |
0.004 |
0.69 | ||
| Abnormal FEV1§, n (%) | 3 (18) | 6 (17) | 0 (0.0) | |
|
|||
| FEV1/FVC z-score‖, median (IQR) | −1.47 (−1.68 to −0.72) | −0.56 (−1.51 to −0.01) | −0.44 (−0.93 to 0.00) |
<0.001 |
0.29 |
0.05 | ||
| FEV1/FVC% predicted‖, median (IQR) | 90 (88 to 95) | 96 (89 to 00) | 97 (94 to 100) |
<0.001 |
0.27 |
0.06 | ||
| Abnormal FEV1/FVC§, n (%) | 5 (29) | 7 (19) | 2 (4) | |
|
|||
| FEF25–75z-score‖, median (IQR) | −1.74 (−2.03 to −1.04) | −0.67 (−1.47 to −0.06) | −0.45 (−0.91 to 0.16) |
<0.001 |
0.23 |
0.08 | ||
| FEF25–75% predicted‖, median (IQR) | 62 (50 to 78) | 85 (68 to 99) | 90 (79 to 104) |
<0.001 |
0.25 |
0.05 | ||
| Abnormal FEF25–75§, n (%) | 9 (53) | 8 (22) | 2 (4) | |||||
Definition of abbreviations: CF = cystic fibrosis; FEF25–75 = forced midexpiratory flow; FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity; HC = healthy control; IQR = interquartile range; LCI = lung clearance index; MBW = multiple breath washout; PCD = primary ciliary dyskinesia.
Ranges for each parameter are as follows: LCI (PCD, 6.80 to 12.77; CF, 6.42 to 16.45; HC, 6.12 to 8.24), FVC z-score (PCD, −2.22 to 2.20; CF, −3.43 to 2.23; HC, −1.39 to 2.72), FVC% predicted (PCD, 66 to 116; CF, 61 to 115; HC, 85 to 122), FEV1 z-score (PCD, −2.96 to 1.34; CF, −2.95 to 1.15; HC, −1.28 to 1.77), FEV1% predicted (PCD, 66 to 116; CF, 61 to 115; HC, 85 to 122), FEV1/FVC z-score (PCD, −2.43 to 0.69; CF, −2.40 to 0.91; HC, −1.77 to 1.27), FEV1/FVC% predicted (PCD, 80 to 104; CF 79 to 105; HC, 87 to 106), FEF25–75 z-score (PCD, −2.97 to 0.59; CF, −1.47 to −0.06; HC, −0.91 to 0.16), FEF25–75% predicted (PCD, 43–113; CF, 20–139; HC, 61–144).
Dwass, Steel, Critchlow-Flinger Method, significance level P < 0.05 denoted in bold typeface.
Coefficients of variation for the LCI 2.5 were 6.01% ± 3.97% for patients with PCD, 6.36% ± 5.41% for children with CF, and 4.34% ± 3.13% for HC children.
Normal cutoff for LCI 7.8, corresponding to z-score +1.645. Normal cutoff for spirometry z-score −1.645.
Calculated using Global Lung Initiative equations.