Table 2. A comparison of the clinical characteristics and biochemical markers of preterm infants with lower bone mass (BMC ≤ 91 g) and higher bone mass (BMC > 91 g) at 3 months corrected age (CA) and the results of univariate logistic regression analysis.
(Data are presented as mean ± SD or number (%).The statistically significant p value are ≤ 0.05.)
| Variable | Total (n = 130) | BMC≤91g (n = 64) | BMC>91g (n = 66) | p value | Odds ratio (95%CI)* | p value |
|---|---|---|---|---|---|---|
| At birth | ||||||
| Gestational age (wks) | 28.7 ± 2.47 | 28.8 ± 2.58 | 28.7 ± 2.38 | 0.879 | 1.02 (0.89–1.17) | 0.782 |
| Birth weight (g) | 1176 ± 354 | 1129 ± 317 | 1223 ± 383 | 0.209 | 0.48 (0.16–1.48) | 0.198 |
| Birth weight z-score | -0.01 ± 0.86 | -0.14 ± 1.03 | 0.11 ± 0.63 | 0.282 | 0.71 (0.46–1.07) | 0.100 |
| Historical cohort (n) | 77 (59.2%) | 34 (53.1%) | 43 (65.2%) | 0.212 | 0.61 (0.30–1.24) | 0.164 |
| Gender: female (n) | 62 (47.7%) | 35 (54.7%) | 27 (40.9%) | 0.160 | 1.74 (0.86–3.52) | 0.117 |
| At term age (~40 weeks PMA) | ||||||
| BPD (n) | 57 (43.9%) | 27 (42.2%) | 30 (45.5%) | 0.727 | 0.88 (0.44–1.76) | 0.707 |
| Steroids (days) | 1.70 ± 4.35 | 2.11 ± 5.39 | 1.30 ± 3.05 | 0.274 | 1.05 (0.96–1.14) | 0.303 |
| Ventilation (days) | 11.8 ± 16.9 | 10.8 ± 14.4 | 12.8 ± 19.1 | 0.623 | 0.99 (0.97–1.01) | 0.505 |
| TPN (days) | 19.7 ± 15.5 | 19.7 ± 17.1 | 19.7 ± 14.0 | 0.849 | 1.00 (0.97–1.03) | 0.996 |
| Baseline iPTH (pg/mL) | 33.8 ± 35.2 | 32.7 ± 34.0 | 34.9 ± 36.5 | 0.246 | 1.00 (0.99–1.01) | 0.718 |
| At 3 mo corrected age | ||||||
| Current age (wks) | 24.2 ± 3.07 | 24.0 ± 3.34 | 24.6 ± 2.81 | 0.307 | 0.99 (0.98–1.01) | 0.308 |
| PMA (weeks) | 52.9 ±1.50 | 52.7 ± 1.64 | 53.2 ± 1.33 | 0.160 | 0.82 (0.64–1.05) | 0.107 |
| Weight (g) | 5534 ± 945 | 5210 ± 722 | 5849 ± 1031 | <0.001 | 0.02 (0.00–0.19) | 0.001 |
| Length(cm) | 60.1 ± 3.85 | 58.8 ± 3.53 | 61.33 ± 3.77 | <0.001 | 0.83 (0.74–0.92) | <0.001 |
| BMC (g) | 95.3 ± 29.8 | 73.4 ± 12.5 | 117 ± 26 | <0.001 | N/A | N/A |
| BMD (g/m2) | 0.38 ± 0.07 | 0.38 ± 0.04 | 0.37 ± 0.09 | 0.787 | 1.99 (0.01–287) | 0.785 |
| BA (m2) | 269 ± 125 | 195 ± 30.2 | 340 ± 139 | <0.001 | 1.21–6 (1.72-9-8.8–4) | p<0.001 |
| Craniotabes, n (%) | 23 (17.7%) | 13 (21%) | 10 (15.9%) | 0.493 | 1.44 (0.57–3.61) | 0.437 |
| Serum Ca (mmol/L) | 2.56 ± 0.11 | 2.55 ± 0.09 | 2.57 ± 0.13 | 0.375 | 0.27 (0.01–7.10) | 0.425 |
| Serum P (mmol/L) | 2.04 ± 0.20 | 2.01 ± 0.20 | 2.08 ± 0.20 | 0.136 | 0.18 (0.03–1.18) | 0.070 |
| UCa/Cr (mg/mg) | 0.49 ± 0.42 | 0.49 ± 0.45 | 0.45 ± 0.41 | 0.728 | 1.07 (0.47–2.46) | 0.863 |
| UP/Cr (mg/mg) | 1.09 ± 1.12 | 0.81 ± 0.86 | 1.37 ± 1.28 | <0.001 | 0.55 (0.35–0.86) | 0.009 |
| TRP (%) | 95.6 ± 5.32 | 97.0 ± 2.97 | 94.3 ± 6.63 | <0.001 | 1.21 (1.07–1.38) | 0.002 |
| ALP (U/L) | 423 ±122 | 426 ± 127 | 419 ± 118 | 0.838 | 1.12 (0.33–3.86) | 0.853 |
| 25-OHD (ng/mL) | 45.4 ± 25.6 | 48.9 ± 32.7 | 41.8 ± 15.0 | 0.950 | 1.01 (1.00–1.03) | 0.123 |
| PTH (pg/mL) | 22.6 ±23.0 | 24.6 ± 27.3 | 20.5 ± 17.4 | 0.426 | 1.01 (0.99–1.03) | 0.348 |
| OC (ng/mL) | 140 ± 54.2 | 158 ± 64.2 | 120 ± 32.0 | 0.001 | 9.72 (2.54–37.18) | 0.001 |
| CTx (ng/mL) | 0.82 ± 0.21 | 0.85 ± 0.22 | 0.79 ± 0.18 | 0.081 | 4.06 (0.59–27.73) | 0.149 |
| PINP (ng/mL) | 3143 ± 870 | 3310 ± 942 | 2973 ± 760 | 0.047 | 3.69 (0.88–15.52) | 0.071 |
| NT-proCNP (pmol/L) | 42.9 ± 18.0 | 43.2 ± 16.4 | 42.49 ± 19.6 | 0.672 | 1.00 (0.98–1.03) | 0.843 |
*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- serum intact parathormone, UCa/Cr—urinary calcium to creatinine ratio in the spot urine sample, UP/Cr—urinary phosphate to creatinine ratio in the spot urine sample, TRP- tubular reabsorption of phosphate, 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