Table 1 Demographic characteristics of the study participants
|  | All Infants (n = 689) | Training Dataset (n = 552) | Validation Dataset (n = 137) | P-value * |
|---|---|---|---|---|
Birth gestation in week (mean ± SD) | 27.6 ± 2.1 | 27.6 ± 2.0 | 27.5 ± 2.1 | 0.832 |
Birth weight in gram (mean ± SD) | 1,034 ± 334 | 1,033 ± 333 | 1,042 ± 352 | 0.814 |
Birth weight z-score (mean ± SD) | 0.09 ± 0.99 | 0.07 ± 1.00 | 0.16 ± 0.97 | 0.888 |
Small for gestational age, n (%) | 58 (8) | 51 (9) | 7 (5) | 0.765 |
Female, n (%) | 346 (50) | 272 (49) | 74 (54) | 0.107 |
Maternal smoking, n (%) | 64 (9) | 52 (9) | 12 (9) | 0.771 |
Surfactant within 24Â h of life, n (%) | 348 (51) | 272 (49) | 76 (55) | 0.216 |
Race/ethnicity, n (%) | Â | Â | Â | 0.161 |
 White | 158 (23) | 129 (23) | 29 (21) | |
 Black | 107 (16) | 83 (15) | 24 (18) | |
 Hispanic | 363 (53) | 291 (53) | 72 (53) | |
 Asian | 36 (5) | 25 (5) | 11 (8) | |
 Other | 25 (4) | 24 (4) | 1 (1) | |
No BPD | 352 (51) | 282 (51) | 70 (51) | 0.335 |
BPD | 337 (49) | 270 (49) | 67 (49) | 0.120 |
 Grade 1 | 176 (26) | 145 (26) | 31 (23) | |
 Grade 2 | 133 (19) | 102 (19) | 31 (23) | |
 Grade 3 or Died | 28 (4) | 23 (4) | 5 (3) |