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The value of use of z-score as a predictor of prognosis of the extrauterine growth restriction

Aim: This study aimed to understand variation of weight Z-score in preterm infants with Extrauterine Growth Restriction (EUGR).

Methods: Inclusion criteria included: 1) gestational age<32 w; 2) more than four w of hospital stay; 3) survived when discharged. All enrolled preterm infants were divided into EUGR group and non-EUGR group according to whether the standard weight at discharge below the 10th percentile of body weight at corrected age. The differences and trends between the two groups were compared. The weight Z-score of preterm infants were calculated at each time point. Weight Z-scores of preterm infants diagnosed EUGR by the Receiver Operating Characteristic (ROC) curve.

Results: 177 preterm infants were enrolled, in which EUGR was 104 cases and the incidence was 58.8%. Weight Z-scores curves of EUGR group were under the curves of all preterm infants and the curves of non-EUGR group were above that. Both weight Z-scores of two groups were negative. The weight Zscores of EUGR group were lower than that of non-EUGR group at each timepoint (all P<0.05). Discharged Z-scores in all premature infants were positively correlated with birth weight(r=0.443, P<0.05). Discharged weight Z-scores in all premature infants were negatively correlated with starting enteral feeding time(r=-0.271), time of full enteral feeding(r=-0.332), time of parenteral nutrition up to 100 Kcal/Kg.d (r=-0.388), Cumulative doses of amino acids (r=-0.298), and cumulative doses of fat milk (r=-2.221) (all P<0.05). The AUC of weight Z-scores predicting EUGR was increased gradually along with prolonged hospitalization. There were statistically significant in weight Z-scores predicting EUGR (all P=0.000) and a high sensitivity and specificity at each timepoint.

Conclusions: Dynamic monitoring weight Z-scores in the preterm infants can show its nutrition and growth trend, and might warn the risk of preterm infant suffering EUGR.

Author(s): Rong Wu, Li-hua Li, Li-jun Xue, Wen-ying Xu, Zhao-fang Tian