Trajectories of the heart rate characteristics index, a physiomarker of sepsis in premature infants, predict Neonatal ICU mortality

This repository contains the dataset and code for the manuscript: Zimmet AM, Sullivan BA, Moorman JR, Lake DE, Ratcliffe SJ. Trajectories of the heart rate characteristics index, a physiomarker of sepsis in premature infants, predict Neonatal ICU mortality. JRSM Cardiovascular Disease 2020. https://doi.org/10.1177/2048004020945142. ABSTRACT OBJECTIVE: Trajectories of physiomarkers over time can be useful to define phenotypes of disease progression and as predictors of clinical outcomes. The aim of this study was to identify phenotypes of the time course of late-onset sepsis in premature infants in Neonatal Intensive Care Units. METHODS: We examined the trajectories of a validated continuous physiomarker, abnormal heart rate characteristics, using functional data analysis and clustering techniques. PARTICIPANTS: We analyzed continuous heart rate characteristics data from 2989 very low birth weight infants (1500 grams) from nine NICUs from 2004-2010. RESULT: Despite the relative homogeneity of the patients, we found extreme variability in the physiomarker trajectories. We identified phenotypes that were indicative of seven and 30 day mortality beyond that predicted by individual heart rate characteristics values or baseline demographic information. CONCLUSION: Time courses of a heart rate characteristics physiomarker reveal snapshots of illness patterns, some of which were more deadly than others. SOURCE OF ORIGINAL DATASET The dataset was originally collected for the following trial of a display of the Heart Rate Characteristics Index (using the HeRO Monitor made by Medical Predictive Science Corporation): Moorman JR, Carlo WA, Kattwinkel J, et al. Mortality Reduction by Heart Rate Characteristic Monitoring in Very Low Birth Weight Neonates: A Randomized Trial. J Pediatr 2011; 159: 900-906.e1. Culture result information was curated originally for the following manuscript: Weitkamp, J., Aschner, J.L., Carlo, W.A. et al. Meningitis, urinary tract, and bloodstream infections in very low birth weight infants enrolled in a heart rate characteristics monitoring trial. Pediatr Res 87, 1226–1230 (2020). https://doi.org/10.1038/s41390-019-0701-4