Prediction of neonatal hyperbilirubinemia by transcutaneous bilirubin nomograms

Abstract

Objective To predict the risk of neonatal hyperbilirubinemia by transcutaneous bilirubin (TcB) nomograms and clinical risk factors. Methods Healthy term and late-preterm newborns (≥ 35 gestational weeks, and birth weight ≥ 2 000 g) born in Guizhou Maternal and Child Care Hospital between January 1, 2013 and December 31, 2013, were included. TcB levels were continuously recorded within 168 hours after birth. The value of hour-specific TcB nomogram combined with receiver operating characteristic (ROC) curves and Logistic regression model for predicting risk of hyperbilirubinemia was evaluated. Pearson's Chi-square test was also used for statistical analysis. Results A total of 5 250 cases were enrolled. TcB increased rapidly in the first 40 hours after birth, slowly increased between 40 to 96 hours, and reached a high level after 96 hours. Among them, the 95th percentile TcB stablized at 96 hours after birth. The 40th, 75th and 95th percentile TcB peak levels were 173, 217 and 248 μmol/L. Among the 5 250 neonates, there were 277 cases (5.3%) in the high-risk zone within 72 hours. The positive predictive value (PPV) was 22.02%; 1 087 cases (20.7%) and 1 854 cases (35.3%) were in the medium-high risk and medium-low risk zones along with the PPV of 10.58% and 3.72%, respectively. There were 2 032 cases (38.7%) in the low-risk zone with the PPV of 1.38%. Multivariate analysis showed that the TcB high-risk zone after 72 hours was associated with gestational age, delivery mode, feeding mode and TcB level of risk zones within 72 hours. Compared to those born at ≥40 gestational weeks, those born at ≥37-<40 gestational weeks were more likely in the TcB high-risk zone after 72 hours (OR=1.80, 95%CI: 1.29-2.51). The likelihood was reduced by 42% among neonates born with cesarean section compared to those delivered vaginally in term of the TcB high-risk zone after 72 hours. Infants who received mixed feeding were less likely to be in the TcB high-risk zone after 72 hours when compared to breast-fed infants (OR=0.51, 95%CI: 0.29-0.88). With the reduction of the high-risk zone level within 72 hours, the likelihood in the TcB high-risk zone after 72 hours was also decreased. ROC curve showed that the area under the curve (AUC) for predicting hyperbilirubinemia was 0.75 and its 95%CI was 0.72-0.78, with a sensitivity of 90.00% and specificity of 40.00%. The AUC of a combination of predictive results obtained by the Logistic regression model with significant variables in univariate analysis and high-risk zone after 72 hours was 0.66, and its 95%CI was 0.62-0.69. AUC estimated by Logistic regression model according to the TcB levels of risk zones within 72 hours combining with clinical risk factors was 0.79, and its 95%CI was 0.76-0.82 (P<0.01). Conclusions Hour-specific TcB nomograms of newborns in our hospital have been obtained, which facilitates the prediction and early intervention of neonatal hyperbilirubinemia. Key words: Hyperbilirubinemia, neonatal; Bilirubin; Risk factors; Forecasting