Hypophosphataemia and late-onset sepsis in extremely preterm neonates: A case-control study

Late-onset sepsis (LOS) is common in extreme prematurity. These infants are at risk of refeeding syndrome-associated hypophosphataemia. Our objective was to investigate whether hypophosphataemia predisposes to LOS in extremely premature neonates.

A retrospective case-control study of neonates born before 29 weeks' gestation in an Australian NICU from 2016 to 2020. Cases developed LOS or localised infection. Two controls, matched within 2 gestational weeks and 90 calendar days, were selected per case.

Amongst 48 cases and 93 controls, cases were smaller at birth (767 g vs. 901 g, P = 0.01), but were otherwise comparable. Hypophosphataemia was more common in cases (26% vs. 15%, P = 0.18). Increased intravenous protein intake in the first week was protective against LOS (OR = 0.9, 95% CI 0.76-1.00, P = 0.04); median 2.1 g/kg/day in cases, 2.3 g/kg/day in controls.

Hypophosphataemia as part of refeeding syndrome is prevalent and under-recognised in extremely premature neonates. We did not find an association between hypophosphataemia and LOS. Low intravenous protein may be an independent risk factor for infection.