Univariate Analysis of Short-Chain Fatty Acids Related to Sudden Infant Death Syndrome

Abstract

Sudden infant death syndrome (SIDS) is defined as the death of a child under one year of age, during sleep, without apparent cause, after exhaustive investigation, so it is a diagnosis of exclusion. SIDS is the principal cause of death in industrialized countries. Inborn errors of metabolism (IEM) have been related to SIDS. These errors are a group of conditions characterized by the accumulation of toxic substances usually produced by an enzyme defect and there are thousands of them and included are the disorders of the β-oxidation cycle, similarly to what can affect the metabolism of different types of fatty acid chain (within these, short chain fatty acids (SCFAs)). In this work, an analysis of postmortem SCFAs profiles of children who died due to SIDS is proposed. Initially, a set of features containing SCFAs information, obtained from the NIH Common Fund's National Metabolomics Data Repository (NMDR) is submitted to an univariate analysis, developing a model based on the relationship between each feature and the binary output (death due to SIDS or not), obtaining 11 univariate models. Then, each model is validated, calculating their receiver operating characteristic curve (ROC curve) and area under the ROC curve (AUC) value. For those features whose models presented an AUC value higher than 0.650, a new multivariate model is constructed, in order to validate its behavior in comparison to the univariate models. In addition, a comparison between this multivariate model and a model developed based on the whole set of features is finally performed. From the results, it can be observed that each SCFA which comprises of the SFCAs profile, has a relationship with SIDS and could help in risk identification.

Keywords: generalized linear model; short-chain fatty acids; sudden infant death syndrome; univariate analysis.

Figure 1

ROC curves obtained through the univariate models of the features that presented an AUC value higher than 0.650: (a) Isubutyric acid, (b) postnatal age weeks (c) butyric acid, (d) hexanoic acid, (e) valeric acid, and (f) acetic acid.

Figure 2

ROC curves obtained through (a) the model containing the complete set of features and (b) the model containing the set of features presenting an AUC value higher than 0.650.