Table 1. Baseline clinical characteristics and biochemical markers of study cohort of preterm infants and a comparison between infants with lower bone mass (BMC ≤ 49 g) and higher bone mass (BMC > 49 g) at term age (40 weeks postmenstrual age).
(Data are presented as the mean ± SD or number (%). The statistically significant p value are ≤ 0.05.).
| Variable | Total (n = 160) | BMC≤49g (n = 83) | BMC>49g (n = 77) | p–value | Odds ratio (95%CI)* | p- value | |
|---|---|---|---|---|---|---|---|
| At birth | |||||||
| Gestational age (wks) | 28.4 ± 2.51 | 28.1 ± 2.43 | 29.0 ± 2.57 | 0.015 | 0.87 (0.76–0.99) | 0.030 | |
| Birth weight (g) | 1139 ± 365 | 1020 ± 298 | 1287 ± 382 | <0.001 | 0.09 (0.03–0.29) | <0.001 | |
| Birth weight z-score | -0.02 ± 0.86 | -0.21 ± 1.00 | 0.21 ± 0.63 | 0.008 | 0.54 (0.36–0.81) | 0.003 | |
| Historical cohort (n) | 115 (62.5%) | 51 (61.4%) | 43 (55.8%) | 0.423 | 1.34 (0.71–2.53) | 0.365 | |
| Gender: female (n) | 84 (45.7%) | 46 (56.6%) | 32 (40.3%) | 0.060 | 1.84 (0.98–3.46) | 0.058 | |
| At term age (~40 weeks PMA) | |||||||
| BPD (n) | 86 (46.7%) | 43 (53.0%) | 28 (35.1%) | 0.109 | 1.97 (1.04–3.73) | 0.036 | |
| Steroids (days) | 1.65 ± 4.10 | 1.42 ± 3.34 | 0.91 ± 2.21 | 0.230 | 1.07 (0.95–1.21) | 0.270 | |
| Ventilation (days) | 13.2 ± 17.2 | 14.7 ± 19.2 | 10.0 ± 13.7 | 0.092 | 1.02 (1.00–1.04) | 0.090 | |
| TPN (days) | 21.3 ± 16.8 | 23.6 ± 17.7 | 16.1 ± 11.4 | 0.002 | 1.04 (1.01–1.07) | 0.004 | |
| Current age (wks) | 11.7 ± 2.94 | 12.1 ± 3.01 | 11.4 ± 2.93 | 0.154 | 1.01 (1.00–1.03) | 0.178 | |
| PMA (wks) | 40.2 ± 1.92 | 40.1 ± 1.97 | 40.4 ± 1.79 | 0.205 | 0.93 (0.79–1.10) | 0.414 | |
| Weight (g) | 3005 ± 653 | 2783 ± 550 | 3329 ± 566 | <0.001 | 0.09 (0.03–0.29) | <0.001 | |
| Length (cm) | 49.5 ± 3.76 | 48.3 ± 3.27 | 50.8 ± 3.77 | <0.001 | 0.81 (0.73–0.90) | <0.001 | |
| BMC (g) | 48.2 ± 10.7 | 40.15 ± 6.51 | 56.9 ± 6.81 | <0.001 | N/A | N/A | |
| BMD (g/cm2) | 0.23 ± 0.05 | 0.21 ±0.05 | 0.25 ± 0.05 | <0.001 | 1.4-7- (1.1-10-1.7–4) | <0.001 | |
| BA (cm2) | 216 ± 53.2 | 198 ± 47.2 | 236 ± 52.6 | <0.001 | 0.02 (0.01–0.13) | <0.001 | |
| Craniotabes n (%) | 36 (19.6%) | 26 (33.3%) | 8 (11.0%) | 0.001 | 4.21 (1.74–10.14) | 0.001 | |
| Serum Ca (mmol/L) | 2.40 ± 0.16 | 2.37 ± 0.16 | 2.45 ± 0.14 | 0.001 | 0.02 (0.00–0.25) | 0.002 | |
| Serum P (mmol/L) | 2.04 ± 0.29 | 2.01 ± 0.29 | 2.09 ± 0.25 | 0.046 | 0.29 (0.08–1.02) | 0.052 | |
| UCa/Crea (mg/mg) | 0.97 ± 0.87 | 0.88 ± 0.78 | 1.15 ± 0.95 | 0.038 | 0.69 (0.47–1.01) | 0.054 | |
| UP/Crea (mg/mg) | 1.46 ± 1.40 | 1.44 ± 1.37 | 1.30 ± 1.17 | 0.800 | 1.09 (0.85–1.40) | 0.479 | |
| TRP (%) | 93.5 ± 7.21 | 93.5 ±6.46 | 94.9 ± 5.02 | 0.438 | 0.96 (0.91–1.01) | 0.142 | |
| ALP (U/L) | 494 ± 283 | 560 ± 357 | 411 ± 122 | 0.004 | 4.69 (1.79–12.28) | 0.002 | |
| 25-OHD (ng/mL) | 43.0 ± 29.2 | 44.1 ± 30.6 | 41.2 ± 22.3 | 0.983 | 1.00 (0.99–1.02) | 0.496 | |
| iPTH (pg/mL) | 39.5 ± 46.5 | 44.3 ± 42.1 | 24.7 ± 14.8 | 0.002 | 1.03 (1.01–1.05) | 0.001 | |
| OC (ng/mL) | 151 ± 61 | 162 ± 69 | 146 ± 52 | 0.210 | 1.62 (0.71–3.69) | 0.246 | |
| CTx (ng/mL) | 0.93 ± 0.27 | 0.95 ±0.27 | 0.90 ± 0.26 | 0.249 | 2.09 (0.61–7.15) | 0.235 | |
| PINP (ng/mL) | 5753 ± 1857 | 5966 ± 1776 | 5494 ± 1615 | 0.092 | 2.49 (0.83–7.43) | 0.101 | |
| NTproCNP (pmol/L) | 64.8 ± 32.7 | 66.8 ± 37.0 | 60.7 ± 28.4 | 0.653 | 1.01 (0.99–1.02) | 0.319 | |
*The results of univariate logistic regression analysis. BPD–bronchopulmonary dysplasia, TPN- total parenteral nutrition, PMA–postmenstrual age, BMC- bone mineral content, BMD- bone mineral density, BA- bone area, iPTH- intact parathormone, UCa/Cr—urinary calcium to creatinine ratio, UP/Cr—urinary phosphates to creatinine ratio, TRP- tubular reabsorptiom of phoasphates, ALP- serum alkaline phosphatase activity, OC—serum osteocalcin, CTx- serum carboxyterminal cross-linked telopeptide of type 1 collagen, PINP- serum procollagen type 1 N-terminal propeptide, NT-proCNP–serum amino-terminal propeptide of C-type natriuretic peptide, N/A- not applicable