Table 2. Characteristics of the Follow-up Cohort and Their Mothers.
| Characteristic | No BPD | BPD | BPD withchronic oxygendependency | p-value† | Confidence Intervals forPairwise Differences* | ||
| Infants | (n = 442) | (n = 144) | (n = 444) | No BPDvs. BPD | No BPD vs. BPDwith chronicoxygen dependency | BPD vs. BPDwith chronicoxygen dependency | |
| Birth weight-grams, median (IQR) | 1070 (930, 1180) | 885 (750, 1060) | 820 (690, 1000) | <0.001 | (90 to 180) | (180 to 245) | (20 to 120) |
| Gestational age -wk, median (IQR) | 29 (27, 30) | 27 (26, 28) | 26 (25, 28) | <0.001 | (1 to 2) | (2 to 3) | (0 to 1) |
| Gestational age at discharge-wk, median (IQR) | 37 (35, 38) | 40 (38, 41) | 39 (37, 41) | <0.001 | (−4 to −2) | (−3 to −2) | (0 to 1) |
| Male sex, no. (%) | 201 (45.5) | 68 (47.2) | 256 (57.7) | <0.001 | (−0.13 to 0.10) | (−0.20 to −0.04) | (−0.22 to 0.01) |
| Singleton, no. (%) | 311 (70.4) | 90 (62.5) | 317 (71.4) | 0.121 | (−0.03 to 0.19) | (−0.08 to 0.06) | (−0.20 to 0.02) |
| Inborn, no. (%) | 396 (89.6) | 124 (86.1) | 391 (88.1) | 0.496 | (−0.04 to 0.11) | (−0.04 to 0.07) | (−0.10 to 0.06) |
| Small for gestational age (<10th %ile), no. (%) | 95 (21.5) | 18 (12.5) | 70 (15.9) | 0.019 | (0.01 to 0.17) | (−0.01 to 0.12) | (−0.11 to 0.04) |
| Surfactant, no. (%) | 168 (38.2) | 95 (66.0) | 333 (75.2) | <0.001 | (−0.39 to −0.17) | (−0.44 to −0.30) | (−0.20 to 0.01) |
| Positive pressure ventilation, (CMV+HFO) no. (%) | 250 (56.6) | 133 (92.4) | 424 (95.5) | <0.001 | (−0.44 to −0.28) | (−0.45 to −0.33) | (−0.09 to 0.03) |
| NCPAP, no. (%) | 170 (38.5) | 107 (74.3) | 368 (82.9) | <0.001 | (−0.46 to −0.26) | (−0.51 to −0.37) | (−0.18 to 0.01) |
| Hospital stay-days, median (IQR) | 56 (43, 71) | 93 (76, 103) | 92 (74, 109) | <0.001 | (−39 to −30) | (−39 to −32) | (−7 to 4) |
| Total ventilation-days, median (IQR) | 1 (0, 6) | 21 (8, 39) | 36 (18, 52) | <0.001 | (−20 to −12) | (−34 to −27) | (−17 to −6) |
| Total suppl. oxygen-days, median (IQR) | 6 (2, 37) | 78 (62, 93) | 209 (153, 277) | <0.001 | (−68 to −56) | (−200 to −177) | (−144 to −112) |
| Total blood transfusions-times, median (IQR) | 0 (0, 1) | 3 (1, 4) | 4 (2, 6) | <0.001 | (−3 to −2) | (−4 to −3) | (−2 to 0) |
| Postnatal steroids, no. (%) | 21 (4.8) | 29 (20.3) | 144 (32.5) | <0.001 | (−0.24 to −0.07) | (−0.34 to −0.22) | (−0.22 to −0.03) |
| Diuretics, no. (%) | 139 (31.6) | 114 (79.7) | 384 (86.5) | <0.001 | (−0.58 to −0.38) | (−0.61 to −0.48) | (−0.16 to 0.02) |
| Patent ductus arteriosus, no. (%) | 117 (26.5) | 89 (61.8) | 307 (69.3) | <0.001 | (−0.46 to −0.24) | (−0.50 to −0.36) | (−0.19 to 0.04) |
| Respiratory distress syndrome, no. (%) | 224 (50.7) | 123 (85.4) | 386 (87.1) | <0.001 | (−0.44 to −0.26) | (−0.43 to −0.30) | (−0.10 to 0.06) |
| Confirmed sepsis, no. (%) | 42 (9.7) | 39 (27.3) | 110 (25.0) | <0.001 | (−0.27 to −0.08) | (−0.21 to −0.09) | (−0.08 to 0.12) |
| Necrotizing enterocolitis, no. (%) | 40 (9.1) | 24 (16.7) | 54 (12.2) | 0.037 | (−0.16 to 0.01) | (−0.08 to 0.02) | (−0.04 to 0.13) |
| Intraventricular hemorrhage grade ≥ III, no. (%) | 10 (2.3) | 11 (7.7) | 41 (9.2) | <0.001 | (−0.11 to 0.002) | (−0.11 to −0.03) | (−0.08 to 0.05) |
| Periventricular leukomalacia, no. (%) | 10 (2.3) | 6 (4.2) | 7 (1.6) | 0.196 | (−0.06 to 0.02) | (−0.02 to 0.03) | (−0.02 to 0.07) |
| Retinopathy of prematurity stage ≥III, no. (%) | 14 (3.6) | 28 (20.4) | 119 (28.0) | <0.001 | (−0.25 to −0.08) | (−0.30 to −0.19) | (−0.17 to 0.02) |
| Maternal | |||||||
| Maternal education more than high school, no. (%) | 252 (60.9) | 79 (57.3) | 253 (59.8) | 0.753 | (−0.08 to 0.15) | (−0.09 to 0.07) | (−0.14 to 0.09) |
| Single parent, no. (%) | 29 (6.6) | 7 (4.9) | 29 (6.6) | 0.735 | (−0.03 to 0.07) | (−0.04 to 0.04) | (−0.07 to 0.03) |
| Blishen score, median (IQR) | 41 (33, 56) | 46 (33, 57) | 44 (33, 57) | 0.227 | (−6 to 1) | (−4 to 1) | (−3 to 4) |
| Maternal race Caucasian, no. (%) | 274 (70.8) | 93 (79.5) | 280 (77.6) | 0.047 | (−0.19 to 0.02) | (−0.14 to 0.01) | (−0.08 to 0.12) |
| Maternal antihypertensive, no. (%) | 101 (23.2) | 14 (10.3) | 75 (17.3) | 0.002 | (0.05 to 0.21) | (−0.01 to 0.12) | (−0.15 to 0.01) |
| Smoking during pregnancy, no. (%) | 121 (28.3) | 39 (27.7) | 102 (23.8) | 0.302 | (−0.10 to 0.11) | (−0.03 to 0.12) | (−0.06 to 0.14) |
| Antenatal corticosteroids, no. (%) | 378 (86.7) | 116 (82.9) | 366 (83.8) | 0.367 | (−0.05 to 0.12) | (−0.03 to 0.09) | (−0.10 to 0.08) |
| Maternal antibiotics, no. (%) | 247 (57.2) | 84 (60.4) | 262 (60.5) | 0.572 | (−0.15 to 0.08) | (−0.11 to 0.05) | (−0.11 to 0.11) |
| Chorioamnionitis, no. (%) | 94 (22.3) | 37 (27.4) | 93 (21.5) | 0.354 | (−0.15 to 0.05) | (−0.06 to 0.08) | (−0.04 to 0.16) |
| Caesarean section, no. (%) | 303 (68.7) | 94 (65.3) | 246 (55.5) | <0.001 | (−0.07 to 0.14) | (0.05 to 0.21) | (−0.01 to 0.21) |
†
Kruskal-Wallis test for continuous variables; Pearson χ2 test for categorical variables.
*Bonferroni correction applied to adjust for the three pairwise comparisons, thus confidence intervals are reported at the (1–0.05/3) % level.
BPD: bronchopulmonary dysplasia; CMV: conventional mechanical ventilation; HFO: high frequency oscillatory ventilation; NCPAP: nasal continuous airways pressure.