Developing a predictive mortality risk algorithm for preterm neonates requiring surgical intervention at Boston Children's Hospital
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INTRODUCTION: Preterm infants have high mortality rates worldwide (Blencowe et al., 2013). The leading causes of infant mortality in the United States are preterm birth, low birth weight, and birth defects (Ely, Driscoll, & Matthews, 2018). The aim of this study is to compare demographics and patient characteristics between surviving and deceased neonates who had fewer than 39 weeks of gestation and required surgical intervention at Boston Children’s Hospital (BCH), and to report clinical characteristics among the deceased population. By identifying significant prognostic factors of mortality in this patient population, a future predictive mortality risk algorithm can be developed. METHODS: After IRB approval, data was obtained from electronic medical records. All patients born before 39 weeks of gestation from 2013-2018 and had a surgical procedure at BCH within the first thirty days of life were included. Demographic characteristics were compared between survivors and deceased patients, and clinical variables are presented among deceased neonates. Statistical testing was done by the Wilcoxon rank sum test and Fisher’s exact test. RESULTS: 653 patients were included in the dataset, 56 of whom were deceased, an 8.6% mortality rate. The median gestational age of the deceased and surviving patients was not statistically different, 35 weeks and 36 weeks respectively (p=0.076). In addition, there was no significant difference between the ratio of males to females between the two groups (p=0.234). However, mortality rates were significantly different across gestational age categories (p=0.015) between deceased and surviving patients. In addition, lower birth weight (p=0.009) and higher ASA classification (an anesthesia preoperative physiological assessment score) (p<0.001) were both independently associated with significantly higher mortality rates. Due to time constraints, only a descriptive analysis could be done on certain clinical variables among the deceased population. Among the deceased group, 62.5% of the surgical procedures were cardiac-related. The median maximum intraoperative lactate value for the entire deceased population was 6.5 mmol/L (IQR: 4.3–8.7). The median age at death was 46 days (IQR: 25-109), and 58.9% of all deceased patients had their care redirected to comfort measures only. Nearly half of the deceased population (27/56; 48.2%) had at least one CPR (cardiopulmonary resuscitation) event. Future analysis will compare these factors against the surviving patients to determine if a significant association with mortality exists. DISCUSSION: The mortality of preterm infants occurs at a high rate. While there were no significant differences between the deceased and surviving groups in terms of gender distribution or gestational age, lower birth weight and higher ASA classification were both independently associated with significantly higher mortality rates; this suggests that the deceased patients were smaller and had more complex medical histories than the surviving group. The majority of deceased patients underwent cardiac-related procedures and most had CPR performed at least once. Further investigation of the entire study population is necessary. A better understanding of the factors that contribute to preterm infant mortality could help families and health professionals to make complex decisions about medical interventions. CONCLUSION: Additional analysis is needed to further identify and better understand patterns in premature neonate mortality at Boston Children’s Hospital.