Renal angina index predicts fluid overload in critically ill children: an observational cohort study

Abstract

Background: Fluid overload and acute kidney injury are common and associated with poor outcomes among critically ill children. The prodrome of renal angina stratifies patients by risk for severe acute kidney injury, but the predictive discrimination for fluid overload is unknown.

Methods: Post-hoc analysis of patients admitted to a tertiary care pediatric intensive care unit (PICU). The primary outcome was the performance of renal angina fulfillment on day of ICU admission to predict fluid overload ≥15% on Day 3.

Results: 77/139 children (55%) fulfilled renal angina (RA+). After adjusting for covariates, RA+ was associated with increased odds of fluid overload on Day 3 (adjusted odds ratio (aOR) 5.1, 95% CI 1.23-21.2, p = 0.025, versus RA-). RA- resulted in a 90% negative predictive value for fluid overload on Day 3. Median fluid overload was significantly higher in RA+ patients with severe acute kidney injury compared to RA+ patients without severe acute kidney injury (% fluid overload on Day 3: 8.8% vs. 0.73%, p = 0.002).

Conclusion: Among critically ill children, fulfillment of renal angina was associated with increased odds of fluid overload versus the absence of renal angina and a higher fluid overload among patients who developed acute kidney injury. Renal angina directed risk classification may identify patients at highest risk for fluid accumulation. Expanded study in larger populations is warranted.

Keywords: Acute kidney injury; Fluid overload; Kidney disease: improving global outcomes; Renal angina index.

Fig. 1

The renal angina index. Adapted from Basu, et al. [10]. Renal angina index is calculated by multiplying the Risk Strata score by the Injury Strata score. The score assigned in the Injury Strata is the highest score based on either the serum creatinine or FO accumulation. The score is calculated at 12 h after ICU admission. FO: Fluid overload, by percentage

Fig. 2

Participant Inclusion. Data are n(%). AKI: Acute kidney injury; ESRD: End Stage Renal Disease; RAI: Renal angina index; FO: Fluid overload

Fig. 3

Cumulative FO percentage among patients over time since ICU admission. AKI: Acute Kidney Injury; FO: Fluid Overload: Hours: Time from ICU admission. *p < 0.05 **p < 0.005 ^p < 0.001.

Fig. 4

Fluid overload phenotype probability by renal angina and acute kidney injury status. RA: Renal Angina; AKI: Severe acute kidney injury; FO: Fluid overload > 15%