Study protocol: optimising newborn nutrition during and after neonatal therapeutic hypothermia in the United Kingdom: observational study of routinely collected data using propensity matching.

Introduction Therapeutic hypothermia is standard of care for infants born >= 36 weeks gestation with hypoxic ischaemic encephalopathy (HIE); consensus on optimum nutrition during therapeutic hypothermia is lacking. This results in variation in enteral feeding and parenteral nutrition (PN) for these infants. In this study, we aim to determine the optimum enteral nutrition and PN strategy for newborns with HIE during therapeutic hypothermia. Methods and analysis We will undertake a retrospective cohort study using routinely recorded electronic patient data held on the United Kingdom (UK) National Neonatal Research Database (NNRD). We will extract data from infants born >= 36 weeks gestational age between 1 January 2008 and 31 December 2016, who received therapeutic hypothermia for at least 72 hours or died during therapeutic hypothermia, in neonatal units in England, Wales and Scotland. We will form matched groups in order to perform two comparisons examining: (1) the risk of NEC between infants enterally fed and infants not enterally fed, during therapeutic hypothermia; (2) the risk of late-onset blood stream infections between infants who received intravenous dextrose without any PN and infants who received PN, during therapeutic hypothermia. The following secondary outcomes will also be examined: survival, length of stay, breast feeding at discharge, hypoglycaemia, time to full enteral feeds and growth. Comparison groups will be matched on demographic, maternal, infant and organisational factors using propensity score matching. Ethics and dissemination In this study, we will use deidentifed data held in the NNRD, an established national population database; parents can opt out of their baby's data being held in the NNRD. This study holds study-specific Research Ethics Committee approval (East Midlands Leicester Central, 17/EM/0307). These results will help inform optimum nutritional management in infants with HIE receiving therapeutic hypothermia; results will be disseminated through conferences, scientific publications and parent-centred information produced in partnership with parents.