Demographic data contrasted between EP/ELBW and control groups and between BPD and no BPD groups within the EP/ELBW cohort
| Variable | EP/ELBW | Control | Comparison | EP/ELBW-BPD | EP/ELBW-no BPD | Comparison |
| n=297 | n=260 | EP/ELBW vs control | n=121 | n=176 | BPD vs no BPD | |
| Antenatal corticosteroids | 73% (216) | 1% (3) | NA | 74% (94) | 72% (126) | 1.11† (0.69, 1.76), 0.67 |
| Birth weight (g) | 888 (161) | 3386 (438) | NA | 840 (175) | 921 (142) | −81* (−118, −44), <0.001 |
| Gestational age (completed weeks) | 26.7 (1.9) | 39.2 (1.4) | NA | 26.0 (1.7) | 27.2 (2.0) | −1.2* (−1.6, −0.8), <0.001 |
| Birth weight z-score | −0.73 (1.19) | −0.02 (0.88) | −0.73* (−0.91, −0.55), <0.001 | −0.63 (1.10) | −0.80 (1.25) | 0.17* (−0.10, 0.44), 0.22 |
| Small for gestational age (<−2 SD) | 15% (46) | 0.4% (1) | 48.1† (6.73, 361), <0.001 | 11% (13) | 19% (33) | 0.52† (0.27, 1.03), 0.06 |
| Male | 46% (137) | 48% (126) | 0.90† (0.64, 1.26), 0.54 | 55% (66) | 40% (71) | 1.75† (1.10, 2.77), 0.017 |
| Multiple birth | 30% (90) | 3% (8) | 13.7† (6.53, 28.9), <0.001 | 31% (38) | 30% (52) | 1.44† (0.84, 2.47), 0.18 |
| Exogenous surfactant | 40% (119) | 0 | NA | 56% (68) | 29% (51) | 3.06† (1.88, 4.99), <0.001 |
| Postnatal corticosteroids | 33% (97) | 0 | NA | 56% (68) | 16% (29) | 6.54† (3.70, 11.5), <0.001 |
| Bronchopulmonary dysplasia‡ | 41% (121) | 0 | NA | NA | NA | |
| Duration of assisted ventilation (days), median (25th–75th centiles) | 26 (11–41) | 0 (0–0) | NA | 36 (25.5–50) | 17 (4–30) | <0.001 |
| At 8 years | ||||||
| Major neurosensory disability§ | 16% (45/274) | 3% (6/221) | 7.04† (2.94, 16.9), <0.001 | 24% (27/111) | 11% (18/163) | 2.56† (1.35, 4.98), 0.004 |
| Expiratory airflow data (n) | 239 | 208 | 89 | 150 | ||
| Asthma | 30% (71) | 21% (43/202) | 1.56† (1.01, 2.42), 0.044 | 35% (31) | 27% (40) | 1.47† (0.83, 2.59), 0.18 |
| Corrected age at assessment (years) | 8.67 (0.34) | 8.89 (0.41) | −0.21* (−0.28, −0.14), <0.001 | 8.58 (0.33) | 8.72 (0.34) | −0.08* (−0.14, −0.02), 0.011 |
| Male | 46% (109) | 47% (97) | 0.94† (0.64, 1.37), 0.74 | 56% (50) | 40% (60) | 1.94† (1.16, 3.26), 0.012 |
| Height (cm) | 129.5 (6.7) | 134.0 (5.7) | −4.5* (−5.6, −3.3), <0.001 | 129.2 (6.8) | 129.7 (6.7) | −0.9* (−2.6, 0.7), 0.28 |
| At 18 years | ||||||
| Expiratory airflow data (n) | 208 | 154 | 77 | 132 | ||
| Asthma | 21% (40/188) | 19% (27/142) | 1.15† (0.57, 1.97), 0.61 | 24% (17/72) | 20% (23/116) | 1.25† (0.61, 2.54), 0.54 |
| Corrected age (years) | 17.94 (0.79) | 18.07 (0.86) | −0.11* (−0.29, 0.07), 0.22 | 17.82 (0.75) | 18.00 (0.81) | −0.13* (−0.29, 0.03), 0.10 |
| Male | 45% (94) | 42% (64) | 1.11† (0.73, 1.70), 0.52 | 57% (44) | 38% (50) | 2.14† (1.24, 3.71), 0.006 |
| Height (cm) | 165.5 (9.8) | 170.8 (9.0) | −5.7* (−7.7, −3.7), <0.001 | 167.8 (10.4) | 164.2 (9.2) | 2.9* (0.6, 5.3), 0.016 |
| At 25 years | ||||||
| Expiratory air airflow data (n) | 164 | 130 | 65 | 99 | ||
| Asthma | 21% (35) | 14% (18) | 1.69† (0.91, 3.14), 0.10 | 15% (10) | 25% (25) | 0.54† (0.24, 1.21), 0.13 |
| Corrected age at assessment (years) | 25.10 (0.75) | 25.27 (0.88) | −0.18* (−0.37, 0.01), 0.065 | 24.98 (0.75) | 25.18 (0.75) | −0.13* (−0.29, 0.03), 0.10 |
| Male | 46% (75) | 44% (57) | 1.04† (0.65, 1.67), 0.86 | 54% (35) | 40% (40) | 1.69† (0.93, 3.06), 0.09 |
| Height (cm) | 166.1 (9.5) | 172.0 (9.1) | −6.2* (−8.4, −4.1), <0.001 | 168.1 (9.9) | 164.8 (9.1) | 3.4* (0.8, 5.9), 0.009 |
| Ethnicity | ||||||
| Caucasian | 91% (150) | 92% (119) | χ2 3df = 3.8, p=0.29¶ | 89% (58) | 93% (92) | χ2 3df = 4.4, p=0.22¶ |
| Black | 2% (4) | 0% (0) | 3% (2) | 2% (2) | ||
| South-East Asian | 3% (5) | 5% (6) | 6% (4) | 1% (1) | ||
| Other | 3% (5) | 4% (5) | 2% (1) | 4% (4) | ||
| Tobacco smoking | 18% (30) | 15% (19) | 1.31† (0.70, 2.45), 0.40 | 25% (16) | 14% (14) | 1.98† (0.89, 4.41), 0.09 |
Data are mean (SD) or % (n), unless otherwise stated. Comparisons from regression models fitted using generalised estimating equations to allow for multiple births, unless stated otherwise.
*Mean difference (95% CI) and p value.
†OR (95% CI) and p value.
‡Oxygen dependency at 36 weeks.
§Any of moderate or severe cerebral palsy, blindness, deafness or an IQ <−2 SD in those assessed at 8 years; .
¶Across all groups.
BPD, bronchopulmonary dysplasia; EP/ELBW, extremely preterm/extremely low birth weight; NA, not applicable as study design means the groups are expected to differ for these variables.