TABLE 3.
COMPARISON OF PRE- AND POSTBRONCHODILATOR RESULTS
| EP: No BPD | EP: BPD | All EP | Classmates (C) | EP – C Δ (95% CI) | EP Only BPD – No BPD Δ (95% CI) | EP No BPD – C P Value* | |
|---|---|---|---|---|---|---|---|
| Baseline, n | 53 | 129 | 182 | 161 | |||
| Respiratory rate, breaths/min | 20 (3) | 20 (3) | 20 (3) | 18 (3) | 2 (1; 3)† | 0.0 (−1; 1) | <0.001 |
| zFEV1‡ | −0.8 (1.3) | −1.7 (1.1) | −1.4 (1.2) | 0.0 (1.0) | −1.5 (−1.7; −1.2)† | – 0.9 (−1.2; −0.5)† | <0.001 |
| FEV1, %pred | 90 (15)% | 80 (13)% | 83 (14)% | 100 (12)% | −17 (−20; −14)%† | −10 (−14; −6)%† | <0.001 |
| zFVC‡ | −0.3 (1.2) | −0.8 (1.2) | −0.7 (1.2) | 0.1 (1.1) | −0.8 (−1.0; −0.6)† | −0.6 (−1.0; −0.2)§ | 0.094 |
| FVC, %pred | 97 (13)% | 91 (13)% | 93 (14)% | 102 (12)% | −9 (−12; −6)%† | −6 (−11; −2)%§ | 0.087 |
| FEV1/FVC | 0.81 (0.09) | 0.78 (0.10) | 0.79 (0.10) | 0.86 (0.07) | −0.07 (−0.09; −0.06)† | −0.04 (−0.07; −0.01)‖ | <0.001 |
| zFEV1/FVC‡ | −0.9 (1.3) | −1.4 (1.3) | −1.3 (1.3) | −0.2 (1.0) | −1.0 (−1.3; −0.8)† | −0.4 (−0.9; −0.03)‖ | <0.001 |
| FEV1/FVC, %pred | 92 (11)% | 88 (11)% | 89 (11)% | 98 (8)% | −9 (−11; −7)%† | −4.0 (−7.6; −0.4)%‖ | <0.001 |
| zFEF25–75§ | −1.5 (1.4) | −2.2 (1.2) | −2.0 (1.3) | −0.5 (1.1) | −1.5 (−1.8; −1.2)† | – 0.7 (−1.1; −0.3)† | <0.001 |
| FEF25–75, %pred | 71 (25)% | 58 (21)% | 61 (23)% | 90 (23)% | 28 (−33; −24)%† | −13 (−20; −6)%† | <0.001 |
| Post BD, n | 45 | 117 | 162 | 149 | |||
| zFEV1 post BD‡ | −0.4 (1.2) | −1.0 (1.0) | −0.8 (1.1) | 0.3 (1.0) | −1.2 (−1.4; −0.9)† | −0.6 (−1.0; −0.3)† | <0.001 |
| Percent change in FEV1 | 5.5 (7.3)% | 10.7 (10.0)% | 9.3 (9.6)% | 4.0 (5.0)% | 5.3 (3.5; 7.0)%† | 5.2 (2.0; 8.5)%§ | 0.58 |
| Change in FEV1 > 12% | 7 [16%] | 37 [32%] | 44 [27%] | 12 [8%] | 19 (11; 27)%† | 16 (3; 30)%‖ | 0.55 |
Definition of abbreviations: Δ (95% CI) = difference in mean or proportion between groups, with 95% confidence interval; BD = bronchodilator; BPD = bronchopulmonary dysplasia; EP = extremely preterm; zFEV1 = FEV1 z-score; FEF25–75 = forced expiratory flow over the middle half of the FVC; zFEF25–75 = FEF25–75 (z-score); zFEV1/FVC = FEV1/FVC (z-score); zFVC = FVC (z-score).
Results are expressed as mean (SD) or n [%]. Boldface entries indicate significance.
Sidak's P value: adjusted for the three comparisons. When BPD versus no BPD in the children born EP were adjusted for the three comparisons, the P values remained in the same categories with the exception of FEV1/FVC (z-score), which had a P value of 0.053. Given the large numbers and greater magnitude of difference in all lung function parameters between BPD and Classmates, these differences were all highly significant but, because of space constraints, are not displayed .
P < 0.001.
Results are expressed as z-scores (23), which adjust for sex, height, and age. %pred = percentage of predicted value, based on Stanojevic and colleagues (23).
P < 0.01.
P < 0.05.