Table 1 Baseline characteristics of cases and matched controls for NEC (matching factors highlighted)
From: Application of the matched nested case-control design to the secondary analysis of trial data
|  | Cases (severe NEC) (n = 35) | Matched controls (n = 140)a | Non-cases (n = 363) |
|---|---|---|---|
Allocated to early arm, n (%) | 17 (48.6) | 74 (52.9) | 182 (50.1) |
Male sex, n (%) | 20 (57.1) | 80 (57.1) | 193 (53.2) |
Gestational age (weeks) | |||
 Median (IQR) | 29 (27 to 31) | 29 (28 to 31) | 32 (29 to 33) |
  < 29 weeks | 16 (45.7) | 61 (43.6) | 69 (19.0) |
  > =29 weeks | 19 (54.3) | 79 (56.4) | 294 (81.0) |
Birth weight (grams) | |||
 Median (IQR) | 750 (660 to 931) | 780 (695 to 890) | 1030 (810 to 1280) |
  < 750 g | 17 (48.6) | 53 (37.9) | 57 (15.7) |
  > =750 g | 18 (51.4) | 87 (62.1) | 306 (84.3) |
Multiple pregnancy, n (%) | |||
 Twins | 5 (14.3) | 26 (18.6) | 83 (22.9) |
 Triplets | 0 | 3 (2.1) | 6 (1.7) |
Pregnancy induced hypertension, n (%) | 13 (37.1) | 69 (49.3) | 145 (40.1) |
 Missing | 0 | 0 | 1 |
Absent/reversed doppler abnormality, n(%) | 35 (100.0) | 138 (98.6) | 347 (95.6) |
Given antenatal steroids, n (%) | 34 (97.1) | 132 (95.7) | 331 (91.4) |
 Missing | 0 | 2 | 1 |
Onset of delivery, n (%) | |||
 Spontaneous | 2 (5.7) | 2 (1.4) | 7 (1.9) |
 Induced | 0 | 1 (0.7) | 4 (1.1) |
 Caesarean | 33 (94.3) | 137 (97.9) | 352 (97.0) |
Apgar score at 5 min | |||
 Median (IQR) | 9 (8 to 9) | 9 (8 to 10) | 9 (9 to 10) |
 Missing | 2 | 2 | 7 |
Ventilated at trial entry, n (%) | 2 (5.7) | 30 (21.4) | 45 (12.4) |
CPAPb at trial entry, n (%) | 22 (62.9) | 78 (55.7) | 122 (33.6) |
UACc in situ at trial entry, n (%) | 11 (31.4) | 35 (25.0) | 44 (12.1) |
UVCd in situ at trial entry, n (%) | 19 (54.3) | 67 (48.6) | 92 (25.4) |
 Missing | 0 | 2 | 1 |
Any diagnosis of severe NECe | 35 (100.0) | 8 (5.7) | 0 |