Urine Output Monitoring for the Diagnosis of Early-Onset Acute Kidney Injury in Very Preterm Infants

Aurélie De Mul; Paloma Parvex; Alice Héneau; Valérie Biran; Antoine Poncet; Olivier Baud; Marie Saint-Faust; Alexandra Wilhelm-Bals

doi:10.2215/CJN.15231121

Urine Output Monitoring for the Diagnosis of Early-Onset Acute Kidney Injury in Very Preterm Infants

Clin J Am Soc Nephrol. 2022 Jul;17(7):949-956. doi: 10.2215/CJN.15231121. Epub 2022 Jun 28.

Authors

Aurélie De Mul¹, Paloma Parvex², Alice Héneau³, Valérie Biran³, Antoine Poncet⁴, Olivier Baud⁵, Marie Saint-Faust⁵, Alexandra Wilhelm-Bals²

Affiliations

¹ Pediatric Nephrology Unit, Geneva University Hospital, Geneva, Switzerland aureliedemul@gmail.com.
² Pediatric Nephrology Unit, Geneva University Hospital, Geneva, Switzerland.
³ Neonatal Intensive Care Unit, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, Université Paris Diderot, Paris, France.
⁴ Clinical Epidemiology Division, Geneva University Hospitals, Geneva, Switzerland.
⁵ Neonatal Intensive Care Unit, Geneva University Hospital, Geneva, Switzerland.

Abstract

Background and objectives: The current threshold used for oliguria in the definition of neonatal AKI has been empirically defined as 1 ml/kg per hour. Urine output criteria are generally poorly documented, resulting in uncertainty in the most accurate threshold to identify AKI in very preterm infants with known tubular immaturity.

Design, setting, participants, & measurements: We conducted a bicentric study including 473 very preterm infants (24^0/7-29^6/7 weeks of gestation) born between January 2014 and December 2018 with urine output measurements every 3 hours during the first 7 days of life and two serum creatinine measurements during the first 10 days of life. AKI was defined using the neonatal Kidney Disease Improving Global Outcomes (KDIGO) definition. We tested whether higher urine output thresholds (1.5 or 2 ml/kg per hour) in modified AKI definitions may better discriminate neonatal mortality compared with the current definition.

Results: Early-onset AKI was developed by 101 of 473 (21%) very preterm infants. AKI was diagnosed on the basis of urine output criteria alone (no rise in creatinine) for 27 of 101 (27%) participants. Early-onset AKI was associated with higher risk of death before discharge (adjusted odds ratio, 3.9; 95% confidence interval, 1.9 to 7.8), and the AKI neonatal KDIGO score showed good discriminative performance for neonatal mortality, with an area under the receiver operating characteristic (ROC) curve of 0.68 (95% confidence interval, 0.61 to 0.75). Modified AKI definitions that included higher urine output thresholds showed significantly improved discriminative performance, with areas under the ROC curve of 0.73 (95% confidence interval, 0.66 to 0.80) for the 1.5-ml/kg per hour threshold and 0.75 (95% confidence interval, 0.68 to 0.81) for the 2-ml/kg per hour threshold.

Conclusions: Early-onset AKI was diagnosed on the basis of urine output exclusively for a quarter of the cases. Furthermore, modified AKI definitions that included higher urine output improved the discriminative performance for predicting mortality.

Keywords: acute kidney injury; early diagnosis; infant; mortality; neonatal KDIGO; preterm; tubular immaturity; urine output; very preterm.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acute Kidney Injury*
Creatinine
Humans
Infant
Infant, Newborn
Infant, Premature*
Infant, Very Low Birth Weight
Oliguria / diagnosis
Oliguria / etiology

Substances

Creatinine