Metabolic Acidosis in Preterm Infants is Associated with a Longer Length of Stay in the Neonatal Intensive Care Unit

INTRODUCTION: Preterm births account for disproportionately high healthcare costs, in large part due to expenses related to length of stay in the hospital neonatal intensive care unit (NICU). It is common for preterm infants to receive human milk fortifier (HMF) while in the NICU. Liquid HMF is available in both acidified and non-acidified formulations. A recent randomized clinical trial found that acidified HMF is associated with an increased incidence of metabolic acidosis, which may contribute to increased costs and longer NICU length of stay. OBJECTIVE: The present study is a secondary analysis of these data, seeking to determine whether additional factors contribute to metabolic acidosis, whether metabolic acidosis is associated with longer hospital length of stay, and whether these associations contribute to the burden of hospital costs. METHODS: The study sample consisted of 152 infants who were hospitalized in US NICUs. Multiple logistic regression was used to model the NICU length of stay. Data from the 2012 Healthcare Cost and Utilization Project (HCUP) Kids’ Inpatient Database (KID) were used to calculate the average cost (charge) per day in a NICU. Costs (charges) were adjusted to $US, year 2018 values, using the health Consumer Price Index. RESULT: Results indicated that acidified HMF was a strong predictor of metabolic acidosis, more so than gestational age or birth weight. Furthermore, metabolic acidosis was associated with incremental NICU costs (charges) of $US19,002 ($US65,462) per infant and longer NICU LOS. CONCLUSION: Future studies should further investigate factors that contribute to NICU length of stay and associated costs of care. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02307760.