Fig. 1

Principal component analysis (PCA) results for the 2–17-year-old cohorts based on the preprocessed original data (where each point represents one patient). a Metabolomic profiling data. b Inflammatory protein mediator profiling data. c Combined biomarker profiling data. The three-dimensional PCA score scatterplots show the distribution of observations (red dots, pediatric intensive care unit sepsis patients; blue dots, emergency department [ED] sepsis patients; green dots, ED controls) in the three-dimensional space formed by principal components PC1, PC2, and PC3. The PCs are the lines in the multivariable dimensional space (variables: metabolites, protein mediators) that best approximate the observations in the least squares sense. The sphere describes the 95 % confidence interval of the Hotelling’s T ² distribution