Nutritional Evaluation and Optimisation in Neonates (NEON) trial of amino acid regimen and intravenous lipid composition in preterm parenteral nutrition: a randomised double-blind controlled trial

Background Parenteral nutrition (PN) is central to the care of very immature infants. Early intakes of higher amounts of amino acids and the use of lipid emulsions containing fish oils are recommended by current international recommendations. Objective To confirm the safety and demonstrate efficacy of the immediate introduction of the recommended daily intake of amino acids (Imm-RDI) and soya bean oil, medium-chain triglycerides, olive oil and fish oil lipid in PN to increase non-adipose (lean) body mass and decrease intrahepatocellular lipid (IHCL) content. Design Multicentre, double-blind, 2 × 2 factorial and randomised controlled trial (RCT). Setting Neonatal units in London and south-east England, UK. Participants Extremely preterm infants born before 31 weeks of gestation without major congenital or life-threatening abnormalities who could to be randomised to receive PN within 24 hours of birth. Interventions Infants were randomised within 24 hours of birth to receive PN containing either high [RDI of amino acids (Imm-RDI)] or low [incremental amino acids (Inc-AA) control] levels of amino acids. In addition, infants were randomised to receive either 20% SMOFlipid® (Fresenius Kabi AG, Richmond Hill, ON, Canada) or 20% Intralipid® (Fresenius Kabi AG, Richmond Hill, ON, Canada) (control). This resulted in four groups: (1) Inc-AA/Intralipid, (2) Inc-AA/SMOFlipid, (3) Imm-RDI/Intralipid and (4) Imm-RDI/SMOFlipid. The intervention was continued until infants were receiving 150 ml/kg/day of enteral feeds for 24 hours. Primary outcome measure For the amino acid intervention, this was non-adipose or lean body mass measured by magnetic resonance imaging. For the lipid composition intervention, this was IHCL content as measured by hepatic magnetic resonance spectroscopy. Primary outcomes were measured at term age equivalent, between 37 and 44 weeks postmenstrual age. Results We randomised 168 infants born before 31 weeks of gestation. We evaluated outcomes, at term, in 133 infants. There were no significant differences in non-adipose mass between the Imm-RDI and Inc-AA groups [adjusted mean difference 1.0 g, 95% confidence interval (CI) –108 to 111 g] or in levels of IHCLs between the SMOFlipid and Intralipid groups (adjusted mean SMOFlipid to Intralipid ratio 1.1, 95% CI 0.8 to 1.6). Infants receiving the Imm-RDI were more likely than Inc-AA infants to have blood urea nitrogen levels > 7 mmol/l [75% vs. 49% (p   10 mmol/l [49% vs. 18% (p < 0.01)]. Furthermore, head circumference at term was smaller in the Imm-RDI group (mean difference –0.8 cm, 95% CI –1.5 to –0.1 cm; p = 0.02). There were no significant differences in any prespecified secondary outcomes, including adiposity, liver function tests, weight, length and mortality. Limitations Not all eligible babies were available for recruitment, as pharmacy staff trained in clinical trial procedures were unavailable at weekends in three of the four centres. We were able to assess brain volumes in only one-third of participants, as imaging was carried out while the participants were sleeping naturally and we measured primary outcomes first and continued to brain imaging only if the infant remained asleep. Conclusions Immediate delivery of the recommended daily intake of parenteral amino acids does not benefit body composition or growth to term and may be harmful; SMOFlipid does not affect IHCL content. Future work The long-term functional outcomes of early administration of RDI of amino acids and the use of SMOFlipid, including neurodevelopment, body composition and metabolic health, should be evaluated.