82–85 cohort* | 91–92 cohort | 99–00 cohort | ||||||||||||||||||||||
Age (mean, range) | 17.7 (15.3–19.9) | 24.9 (22.5–27.0) | 34.5 (32.1–37.6) | 10.6 (9.7–11.5) | 17.8 (17.0–19.2) | 27.1 (26.1–28.4) | 11.6 (10.1–13.8) | 19.8 (18.2–21.4) | ||||||||||||||||
n/eligble | ||||||||||||||||||||||||
Term-born | 46/46 | 40/46 | 34/46 | 35/35 | 28/35 | 26/34 | 54/57 | 43/57 | ||||||||||||||||
EP no BPD | 34/38 | 32–33/38 | 25–26/36 | 23/23 | 19/23 | 15/23 | 26/43 | 27/43 | ||||||||||||||||
EP BPD | 12/13 | 12/13 | 9–10/12 | 12/12 | 12/12 | 9/12 | 32/45 | 23/45 | ||||||||||||||||
Mean | 95% CI | P value | Mean | 95% CI | P value | Mean | 95% CI | P value | Mean | 95% CI | P value | Mean | 95% CI | P value | Mean | 95% CI | P value | Mean | 95% CI | P value | Mean | 95% CI | P value | |
FEV1 z-score | ||||||||||||||||||||||||
Term-born (ref) | 0.0 | −0.3 to 0.3 | − | −0.1 | −0.4 to 0.2 | − | 0.1 | −0.2 to 0.4 | − | −0.1 | −0.4 to 0.3 | − | −0.2 | −0.6 to 0.1 | − | 0.1 | −0.2 to 0.5 | − | −0.3 | −0.6 to −0.1 | − | −0.1 | −0.4 to 0.2 | − |
EP no BPD | −1.1 | −1.5 to −0.8 | <0.001 | −0.9 | −1.2 to −0.6 | <0.001 | −0.9 | −1.2 to −0.5 | <0.001 | −0.6 | −1.0 to −0.1 | 0.07 | −0.6 | −1.1 to −0.2 | 0.17 | −0.4 | −0.8 to 0.1 | 0.08 | −0.6 | −0.9 to −0.2 | 0.33 | −0.5 | −0.9 to −0.2 | 0.07 |
EP BPD | −1.5 | −2.1 to −1.0 | <0.001 | −1.4 | −1.9 to −0.8 | <0.001 | −1.6 | −2.2 to −1.0 | <0.001 | −1.5 | −2.1 to −0.9 | <0.001 | −1.4 | −2.0 to −0.9 | <0.001 | −1.5 | −2.1 to −0.9 | <0.001 | −0.7 | −1.1 to −0.4 | 0.08 | −0.6 | −1.0 to −0.3 | 0.03 |
FVC z-score | ||||||||||||||||||||||||
Term-born (ref) | −0.2 | −0.5 to 0.1 | − | 0.0 | −0.3 to 0.3 | − | 0.2 | −0.2 to 0.5 | − | −0.1 | −0.5 to 0.2 | − | −0.2 | −0.6 to 0.2 | − | 0.4 | 0.1 to 0.8 | − | −0.2 | −0.4 to 0.1 | − | 0.0 | −0.3 to 0.3 | − |
EP no BPD | −0.9 | −1.3 to −0.6 | 0.003 | −0.4 | −0.7 to 0.0 | 0.11 | −0.3 | −0.7 to 0.0 | 0.05 | −0.5 | −1.0 to −0.1 | 0.17 | −0.4 | −0.9 to 0.0 | 0.41 | −0.1 | −0.5 to 0.4 | 0.07 | −0.1 | −0.5 to 0.3 | 0.67 | −0.1 | −0.5 to 0.3 | 0.66 |
EP BPD | −1.1 | −1.6 to −0.5 | 0.01 | −0.6 | −1.2 to 0.0 | 0.07 | −0.9 | −1.5 to −0.3 | 0.002 | −0.7 | −1.2 to −0.1 | 0.15 | −0.2 | −0.8 to 0.4 | 0.95 | −0.1 | −0.7 to 0.5 | 0.12 | −0.2 | −0.5 to 0.2 | 0.96 | −0.3 | −0.7 to 0.1 | 0.20 |
FEV1/FVC z-score | ||||||||||||||||||||||||
Term-born (ref) | 0.4 | 0.1 to 0.6 | − | −0.2 | −0.4 to 0.1 | − | −0.2 | −0.5 to 0.1 | − | 0.1 | −0.2 to 0.4 | − | −0.1 | −0.5 to 0.2 | − | −0.5 | −0.9 to −0.2 | − | −0.3 | −0.6 to 0.0 | − | −0.2 | −0.5 to 0.0 | − |
EP no BPD | −0.3 | −0.7 to 0.0 | 0.002 | −0.9 | −1.3 to −0.6 | <0.001 | −0.9 | −1.3 to −0.5 | 0.004 | 0.0 | −0.4 to 0.4 | 0.73 | −0.3 | −0.7 to 0.2 | 0.55 | −0.5 | −1.0 to −0.1 | 0.96 | −0.8 | −1.2 to −0.4 | 0.03 | −0.7 | −1.1 to −0.3 | 0.06 |
EP BPD | −0.7 | −1.2 to −0.1 | 0.001 | −1.0 | −1.6 to −0.5 | 0.007 | −1.2 | −1.8 to −0.6 | 0.003 | −1.4 | −2.0 to −0.8 | <0.001 | −1.7 | −2.3 to −1.2 | <0.001 | −1.9 | −2.5 to −1.3 | <0.001 | −0.9 | −1.2 to −0.6 | 0.008 | −0.5 | −0.9 to −0.1 | 0.30 |
FEF 25–75% z-score | ||||||||||||||||||||||||
Term-born (ref) | 0.2 | −0.1 to 0.5 | − | −0.1 | −0.4 to 0.2 | − | −0.1 | −0.4 to 0.2 | − | −0.2 | −0.6 to 0.1 | − | −0.3 | −0.7 to 0.0 | − | −0.4 | −0.8 to −0.1 | − | −0.6 | −0.8 to −0.3 | − | −0.3 | −0.5 to 0.0 | − |
EP no BPD | −1.0 | −1.3 to −0.7 | <0.001 | −1.2 | −1.6 to −0.9 | <0.001 | −1.1 | −1.5 to −0.8 | <0.001 | −0.8 | −1.2 to −0.4 | 0.05 | −0.6 | −1.0 to −0.2 | 0.32 | −0.7 | −1.1 to −0.2 | 0.35 | −1.0 | −1.3 to −0.6 | 0.06 | −0.8 | −1.2 to −0.4 | 0.02 |
EP BPD | −1.5 | −2.0 to −0.9 | <0.001 | −1.5 | −2.0 to −0.9 | <0.001 | −1.6 | −2.2 to −1.1 | <0.001 | −1.9 | −2.5 to −1.4 | <0.001 | −1.9 | −2.5 to −1.4 | <0.001 | −2.1 | −2.7 to −1.5 | <0.001 | −1.2 | −1.6 to −0.9 | 0.003 | −0.9 | −1.3 to −0.5 | 0.007 |
All results are based on longitudinal mixed-effects models. The p values compare EP subjects with controls.
*Two of the eligible non-participants could not be classified according to BPD status, but are presented in the non-BPD group.
BPD, bronchopulmonary dysplasia (supplemental oxygen or respiratory support at postmenstrual age ≥36 weeks); EP, subjects born extremely preterm or with extremely low birth weight (gestational age ≤28 weeks or birth weight ≤1000 g); FEF25–75%, forced expiratory flow at 25%–75% of FVC; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; ref, reference level.