Table 1.
Comparison and risk analysis of clinical characteristics in very low birth weight infants according to L-thyroxine administration for thyroid dysfunction.
| Clinical Characteristics | Total (N = 5635) |
LT4 (+) (N = 490) |
LT4 (−) (N = 5145) |
p | Odds Ratio | 95% CI | *p | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| N, Mean | %, SD | N, Mean | %, SD | N, Mean | %, SD | Lower | Upper | |||||
| Demographic Factor | ||||||||||||
| Gestational age (weeks) | 28.63 | 2.24 | 28.09 | 2.45 | 28.68 | 2.21 | <0.001 | 1.124 | 1.079 | 1.171 | <0.001 | |
| Birth weight (g) | 1091.0 | 261.3 | 955.0 | 275.2 | 1103.9 | 256.2 | <0.001 | 1.000 | 1.000 | 1.000 | <0.001 | |
| Small for gestational age | 710 | 12.6 | 110 | 22.4 | 600 | 11.7 | <0.001 | 2.193 | 1.745 | 2.756 | <0.001 | |
| Male | 2837 | 50.3 | 234 | 47.8 | 2603 | 50.6 | 0.237 | |||||
| Vaginal delivery | 1207 | 21.4 | 115 | 23.5 | 1092 | 21.2 | 0.249 | |||||
| 5′ Apgar score (0–3) | 269 | 4.8 | 32 | 6.6 | 237 | 4.6 | 0.016 | 1.555 | 1.055 | 2.290 | 0.026 | |
| In vitro fertilization | 1371 | 24.3 | 132 | 26.9 | 1239 | 24.1 | 0.168 | |||||
| Multigestation | 2021 | 35.7 | 202 | 41.2 | 1809 | 35.2 | 0.009 | 1.293 | 1.071 | 1.562 | 0.008 | |
| maternal DM | 549 | 9.7 | 36 | 7.3 | 513 | 10.0 | 0.066 | |||||
| Maternal HTN | 1189 | 21.1 | 102 | 20.8 | 1087 | 21.1 | 0.908 | |||||
| Chorioamnionitis | 1812 | 37.8 | 161 | 38.1 | 1651 | 37.8 | 0.916 | |||||
| PROM | 2090 | 37.3 | 160 | 33.1 | 1930 | 37.7 | 0.049 | 0.819 | 0.672 | 0.998 | 0.047 | |
| Prenatal steroid | 4744 | 85.4 | 423 | 87.4 | 4321 | 85.2 | 0.201 | |||||
| Outborn | 173 | 3.1 | 22 | 4.5 | 151 | 2.9 | 0.073 | |||||
| Neonatal Morbidities and Related Treatment | ||||||||||||
| Respiratory | RDS | 4644 | 82.4 | 404 | 82.4 | 4240 | 82.4 | 1.00 | ||||
| PPHN | 291 | 5.2 | 52 | 10.6 | 239 | 4.6 | <0.001 | 2.437 | 1.778 | 3.341 | <0.001 | |
| BPD | 1809 | 32.2 | 213 | 43.7 | 1596 | 31.1 | <0.001 | 1.732 | 1.427 | 2.081 | <0.001 | |
| Cardiovascular | Drugs for PDA | 1960 | 48.5 | 208 | 58.6 | 1752 | 47.5 | <0.001 | 1.564 | 1.254 | 1.950 | <0.001 |
| Hypotension | 1076 | 19.1 | 140 | 28.6 | 936 | 18.2 | <0.001 | 1.799 | 1.460 | 2.215 | <0.001 | |
| Neurologic | Seizure | 310 | 5.5 | 55 | 11.2 | 255 | 5.0 | <0.001 | 2.425 | 1.783 | 3.279 | <0.001 |
| IVH ≥ 3 | 336 | 6.0 | 34 | 6.9 | 302 | 5.9 | 0.319 | |||||
| PVL | 410 | 7.3 | 44 | 9.0 | 366 | 7.1 | 0.145 | |||||
| Gastrointestinal/Nutritional | NEC ≥ st2 | 291 | 5.2 | 32 | 6.5 | 259 | 5.0 | 0.164 | 1.318 | 0.902 | 1.926 | 0.154 |
| PN ≥4 weeks | 2160 | 38.3 | 220 | 44.9 | 1940 | 37.7 | 0.002 | 1.346 | 1.117 | 1.622 | 0.002 | |
| Others | Sepsis | 1179 | 20.9 | 133 | 27.1 | 1046 | 20.3 | 0.004 | 1.460 | 1.183 | 1.801 | <0.001 |
| Operation | 1144 | 20.3 | 153 | 31.2 | 991 | 19.3 | <0.001 | 1.903 | 1.553 | 2.332 | <0.001 | |
| RBC transfusion | 3845 | 68.2 | 379 | 77.3 | 3466 | 67.4 | <0.001 | 1.654 | 1.328 | 2.060 | <0.001 | |
| Outcomes at Discharge and 2–3 Years of Age | ||||||||||||
| Discharge (EUGR) |
Hospital stays (day) | 75.5 | 37.1 | 90.8 | 48.5 | 74.3 | 35.6 | <0.001 | 1.009 | 1.007 | 1.011 | <0.001 |
| Weight (n = 5635) | 3190 | 56.6 | 351 | 71.6 | 2839 | 55.2 | <0.001 | 2.051 | 1.673 | 2.515 | <0.001 | |
| Length (n = 5205) | 3393 | 65.2 | 363 | 78.6 | 3030 | 63.9 | <0.001 | 2.073 | 1.647 | 2.609 | <0.001 | |
| HC (n = 5360) | 2351 | 43.9 | 289 | 61.8 | 2062 | 42.2 | <0.001 | 2.216 | 1.824 | 2.693 | <0.001 | |
| FU1 or FU2 (GR < 5 p) |
Weight (n = 5251) | 840 | 16.0 | 146 | 30.5 | 694 | 14.5 | <0.001 | 2.575 | 2.086 | 3.178 | <0.001 |
| Height (n = 4904) | 894 | 18.2 | 138 | 29.7 | 756 | 17.0 | <0.001 | 2.055 | 1.660 | 2.565 | <0.001 | |
| HC (n = 4164) | 643 | 15.5 | 107 | 27.0 | 536 | 14.3 | <0.001 | 2.219 | 1.746 | 2.821 | <0.001 | |
| AED (n= 5093) |
69 | 1.2 | 11 | 2.3 | 58 | 1.1 | 0.047 | 2.032 | 1.059 | 3.898 | 0.033 | |
| FU1 or FU2 (Developmental delay) | Cerebral palsy (n = 4987) |
345 | 6.3 | 46 | 9.6 | 299 | 6.0 | 0.004 | 1.658 | 1.197 | 2.296 | 0.002 |
| Cognitive delay (n = 3946) |
1165 | 29.5 | 140 | 36.9 | 1025 | 28.7 | 0.001 | 1.453 | 1.165 | 1.812 | 0.001 | |
p value was obtained by Fisher’s exact test or Mann–Whitney U test. *p value was obtained by univariate linear or non-linear logistic regression analysis. Abbreviations and meanings: LT4, L-thyroxine; Multigestation, two or more fetuses in a pregnancy; Maternal DM, gestational diabetes or overt diabetes mellitus of mother; Maternal HTN, pregnancy-induced hypertension or essential hypertension; PROM, premature rupture of membrane; Prenatal steroid, completed or incomplete corticosteroid injection to mother before giving birth; RDS, respiratory distress syndrome; PPHN, persistent pulmonary hypertension; BPD, bronchopulmonary dysplasia; Drugs for PDA, ibuprofen, indomethacin and other nonsteroid anti-inflammatory drugs for closing patent ductus arteriosus therapeutically or prophylactically; Hypotension, hypotension (a mean arterial pressure (MAP) below that for the gestational age or a MAP < 30 mmHg within a week after birth) treated with medications including inotropes such as dopamine, dobutamine, or epinephrine, hydrocortisone, and others; Seizure, neonatal seizure requiring antiepileptic drugs; IVH ≥ 3, intraventricular hemorrhage ≥ grade 3; PVL, periventricular leukomalacia; PN ≥ 4 weeks, parenteral nutrition duration of ≥ 4 weeks; Sepsis, antibiotics for ≥ 5 days and positive result of blood culture; Operation, ligation of PDA, laparotomy of spontaneous intestinal perforation or NEC, or surgery for ROP; RBC transfusion, red blood cell transfusion; EUGR, extrauterine growth retardation; HC, head circumference; FU, follow up; GR < 5 p, growth retardation < 5th percentile of weight, height or HC at FU1 or 2; AED, antiepileptic drug; Cerebral palsy, any types of quadriplegia, diplegia or hemiplegia; Cognitive delay, Bayley II Mental Developmental Index (MDI) < 70, Bayley III cognitive composite scores < 85, or the cognitive domain of K-DST < −1 SD.