Renal outcome in children born preterm with neonatal acute renal failure: IRENEO-a prospective controlled study

Acute kidney injury (AKI) is a severe complication of prematurity, with currently unknown consequences for renal function in childhood. The objective of this study was to search for signs of reduced nephron number in children aged 3-10 years who had been born preterm with neonatal AKI and compare this group to control children.

IRENEO was a prospective, controlled study conducted in 2013 in Nantes University Hospital. Children who were born at less than 33 weeks gestational age (GA) and included in the LIFT cohort were eligible for entry. Twenty-five children with AKI (AKI-C) and 49 no-AKI children were matched on a propensity score of neonatal AKI and age. AKI was defined as a serum creatinine level higher than critical values: 1.6 mg/dl (GA 24-27 weeks), 1.1 mg/dl (28-29) and 1 mg/dl (GA 30-32). Renal function was evaluated during childhood.

Mean age of the children at the time of the study was 6.6 years. No difference in microalbuminuria, estimated glomerular filtration rate (GFR) or pulse wave velocity was observed between the two groups. Renal volume was lower in the AKI-C group (57 vs. 68; p = 0.04). In the entire cohort, 10.8 % had a microalbuminuria, and 23 % had a diminished GFR (median 79 ml/min/1.73 m²). The GFR was lower in children with very low birth weight of <1000 g (99 vs. 107 ml/min/1.73 m²; p = 0.04).

In children born preterm, neonatal AKI does not seem to influence renal function. However, independent ofAKI, a large proportion of very preterm infants, especially those with very low birth weight, presented with signs of nephron reduction, thus requiring follow-up with a nephrologist.