Expiratory airflows at 25 years of age contrasted between EP/ELBW and control groups and between BPD and no BPD groups within the EP/ELBW cohort
| Flow variable | EP/ELBW n=164 | Control n=130 | Mean difference (95% CI), P value* | BPD n=65 | No BPD n=99 | Mean difference (95% CI), P value* |
| FEV1 | ||||||
| z-Score | −0.96 (1.22) | 0.03 (1.01) | −0.97 (−1.23 to −0.71), <0.001 | −1.36 (1.18) | −0.70 (1.17) | −0.66 (−0.99 to −0.33), <0.001 |
| % Predicted | 88.4 (14.6) | 100.3 (11.9) | −11.6 (−14.7 to −8.5), <0.001 | 83.6 (14.3) | 91.6 (14.0) | −8.0 (−12.0 to −4.0), <0.001 |
| Percentile | 27.6 (26.3) | 49.8 (27.6) | −21.7 (−28.0 to −15.2), <0.001 | 18.9 (20.1) | 33.3 (28.4) | −14.6 (−21.5 to −7.7), <0.001 |
| FVC | ||||||
| z-Score | −0.08 (1.04) | 0.24 (0.93) | −0.33 (−0.56 to −0.10), 0.005 | −0.24 (1.21) | 0.02 (0.91) | −0.26 (−0.59 to 0.06), 0.11 |
| % Predicted | 99.1 (12.5) | 103.0 (11.4) | −4.0 (−6.7 to −1.2), 0.005 | 97.3 (14.5) | 100.3 (10.9) | −3.0 (−6.9 to 0.8), 0.12 |
| Percentile | 48.1 (28.3) | 56.4 (26.5) | −8.4 (−14.8 to −2.1), 0.009 | 43.3 (30.8) | 51.2 (26.2) | −7.3 (−15.6 to 1.0), 0.08 |
| FEV1:FVC | ||||||
| z-Score | −1.27 (1.19) | −0.31 (1.02) | −0.96 (−1.23 to −0.69), <0.001† | −1.61 (1.19) | −1.05 (1.14) | −0.55 (−0.92 to −0.19), 0.003† |
| % Predicted | 88.8 (10.8) | 97.1 (8.3) | −8.3 (−10.6 to −5.9), <0.001† | 85.8 (11.0) | 90.8 (10.2) | −5.0 (−8.3 to −1.7), 0.003† |
| Percentile | 20.5 (24.3) | 41.1 (27.3) | −20.0 (−26.1 to −14.0), <0.001 | 14.9 (22.8) | 24.2 (24.7) | −9.3 (−16.8 to −1.7), 0.016† |
| Ratio | 0.762 (0.096) | 0.829 (0.073) | −0.067 (−0.088 to −0.047), <0.001 | 0.735 (0.095) | 0.780 (0.092) | −0.045 (−0.075 to −0.016), 0.003 |
| FEF25%−75% | ||||||
| z-Score | −1.47 (1.25) | −0.27 (1.02) | −1.20 (−1.47 to −0.93), <0.001† | −1.88 (1.23) | −1.21 (1.20) | −0.67 (−1.05 to −0.28), 0.001† |
| % Predicted | 70.1 (24.6) | 94.8 (22.8) | −24.0 (−19.5 to −18.5), <0.001 | 62.5 (23.3) | 75.0 (24.2) | −12.5 (−20.0 to −5.0), 0.001† |
| Percentile | 18.1 (22.7) | 42.2 (27.7) | −23.7 (−29.7 to −17.7), <0.001 | 12.1 (18.7) | 22.0 (24.3) | −14.1 (−23.2 to −5.1), 0.002 |
Data are mean (SD), unless otherwise specified.
*From separate regression models for each outcome fitted using generalised estimating equations to allow for multiple births.
†Model would not converge; hence, results from standard regression models with error terms adjusted for multiple births.
BPD, bronchopulmonary dysplasia; EP/ELBW, extremely preterm/extremely low birth weight; FEF25%−75%, airflow between 25% and 75% of the vital capacity.