Figure 1.
Flow diagram detailing enrolment of study infants.
Table 1.
Demographic Details of Study Population.
Figure 2.
A comparison plot of percentage increase in metabolite concentration for metabolites that significantly differed in either the asphyxia vs. matched control comparison (squares), the HIE vs. matched controls (triangles), or both comparisons (circles).
Figure 3.
Canonical Variate Analysis for the combined data sets.
Squares = asphyxia cases; Circles = matched asphyxia controls; Triangles = HIE cases; Diamonds = matched HIE controls. Solid circles = 95% confidence intervals for each group population; Dashed circles = 95% confidence intervals for the mean of each group.
Table 2.
Metabolites Identified as significantly altered in Umbilical Cord Blood Samples of Cases compared to Matched Controls.
Figure 4.
The predictive scores for a PLS-DA model built to discriminate between HIE versus all other outcomes (asphyxia and both the control groups) using the complete data set.
The PLS score box plot is grouped by Sarnat score. Here a Sarnat score of zero is equivalent to the “asphyxia” classification, and Sarnat grade of 1, 2 and 3 represent the 3 levels of increasing HIE severity. The model was optimally built using 2 latent factors. The model had an R2 = 0.32, Q2 = 0.22, and an AUC of 0.92 (95% CI: 0.84–0.97). For a fixed specificity of 0.95 the corresponding sensitivity for predicting HIE (at any level) is 0.75 (95% CI: 0.55–0.88), the corresponding decision boundary is indicated by a dashed line in the boxplot. Note: the Quality Control samples (repeated injection of serum from two control patients: QC1 & QC2) are projected through the PLS-DA model and the subsequent predictions give an estimation of model precision.
Figure 5.
Variable importance plot for the HIE versus ‘all other outcomes’ PLD-DA model.
A VIP score >1 indicates an important contribution to the model.
Figure 6.
A ROC comparison of all models produced in this study.
Triangle = PLS-DA: HIE versus matched controls, AUC = 0.96 (95% CI = 0.83–1.00); Square = PLS-DA: Asphyxia versus matched controls, AUC = 0.91 (0.83–0.96); Diamond = PLS-DA: HIE versus ‘all other outcomes’ (all metabolites), AUC = 0.91 (0.83–0.96); Circle = Logistic Regression: HIE versus ‘all other outcomes’ (5 metabolites), AUC = 0.92 (0.84–0.97). For clarity the convex-hull ROC curve approximations are shown. All AUC calculations were made on the actual predicted values.
Table 3.
Logistic regression model for HIE versus ‘all other outcomes’: AUC of 0.92 (95% CI: 0.83–0.96) A specificity of 0.95 produced a corresponding sensitivity of 0.72 (95% CI: 0.54–0.88).