A modified renal angina index in critically ill patients with COVID-19

Abstract

Background

The renal angina index (RAI) is a tool that has been validated by several studies in the pediatric population to predict the development of severe acute kidney injury (AKI). The aims of this study were to evaluate the efficacy of the RAI in predicting severe AKI in critically ill patients with COVID-19 and to propose a modified RAI (mRAI) for this population.

Methods

This was a prospective cohort analysis of all COVID-19 patients receiving invasive mechanical ventilation (IMV) who were admitted to the intensive care unit (ICU) of a third-level hospital in Mexico City from 03/2020 to 01/2021. AKI was defined according to KDIGO guidelines. The RAI score was calculated for all enrolled patients using the method of Matsuura. Since all patients had the highest score for the condition (due to receiving IMV), the score corresponded to the delta creatinine (ΔSCr) value. The main outcome was severe AKI (stage 2 or 3) at 24 and 72 h after ICU admission. A logistic regression analysis was applied to search for factors associated with the development of severe AKI, and the data were applied to develop a mRAI and compare it vis-à-vis the efficacy of both scores (RAI and mRAI).

Results

Of the 452 patients studied, 30% developed severe AKI. The original RAI score was associated with AUCs of 0.67 and 0.73 at 24 h and 72 h, respectively, with a cutoff of 10 points to predict severe AKI. In the multivariate analysis adjusted for age and sex, a BMI ≥30 kg/m², a SOFA score ≥6, and Charlson score were identified as risk factors for the development of severe AKI. In the new proposed score (mRAI), the conditions were summed and multiplied by the ΔSCr value. With these modifications, the AUC improved to 0.72 and 0.75 at 24 h and 72 h, respectively, with a cutoff of 8 points.

Conclusions

The original RAI is a limited tool for patients with critical COVID-19 receiving IMV. The mRAI, with the parameters proposed in the present study, improves predictive performance and risk stratification in critically ill patients receiving IMV.

Keywords:

• COVID-19
• acute kidney injury
• renal angina index
• modified renal anginal index

Acknowledgements

An abstract based on this work was presented in poster form at the 2022 American Society of Nephrology Kidney Week in Orlando, Florida. The abstract is available at the following link: https://www.asn-online.org/education/kidneyweek/2022/program-abstract.aspx?controlId=3769929

Ethical approval

The study was performed in accordance with the Declaration of Helsinki and approved by the research ethics and bioethics committees (NMM-3325-20-20-1 and CEI-011-20160627, respectively) of the Instituto Nacional de Ciencias Médicas y Nutrición, Salvador Zubirán, Mexico City.

Consent form

Written informed consent was obtained from the patients or relatives upon admission to the hospital, for using the information and applying those medical procedures specific for the health contingency.

Author contributions

Concept and study design: O.V.V. and N.T.C.; supervision: O.V.V. and N.T.C.; data collection: N.B.P., A.U.P., and A.C.I.; analysis and interpretations: N.T.C. and O.V.V.; writing: N.B.P. and N.T.C.; critical review: O.V.V. All authors read and approved the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analyzed during this study are included in this article. Further enquiries can be directed to the corresponding author.

Additional information

Funding

The authors declared that this study has received no financial support.