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Kidney Week

Abstract: FR-OR08

AKI Diagnostic Accuracy and Implications of AKI Baseline Creatinine (ABC) vs. Other Baseline Creatinine Estimating Equations

Session Information

Category: Acute Kidney Injury

  • 101 AKI: Epidemiology, Risk Factors, and Prevention

Authors

  • Bjornstad, Erica C., The University of Alabama at Birmingham Department of Pediatrics, Birmingham, Alabama, United States
  • Acharjee, Mithun Kumar, The University of Alabama at Birmingham Department of Biostatistics, Birmingham, Alabama, United States
  • Rahman, Akm Fazlur, The University of Alabama at Birmingham Department of Biostatistics, Birmingham, Alabama, United States
  • Zappitelli, Michael, Toronto Hospital for Sick Children, Toronto, Ontario, Canada
  • Basu, Rajit K., Ann and Robert H Lurie Children's Hospital of Chicago, Chicago, Illinois, United States
  • Schwartz, George J., University of Rochester, Rochester, New York, United States
  • Goldstein, Stuart, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
  • Braun, Chloe Grace, The University of Alabama at Birmingham Department of Pediatrics, Birmingham, Alabama, United States
  • Askenazi, David J., The University of Alabama at Birmingham Department of Pediatrics, Birmingham, Alabama, United States
Background

Acute kidney injury (AKI) definitions rely on a known baseline creatinine (Crb), which is missing in up to 75% of hospitalized children. A new method (ABC equation) for estimating Crb was derived from children without kidney disease. We aim to externally validate the ABC method in an international cohort and assess how different Crb estimating equations alter AKI epidemiology.

Methods

AWARE is a prospective international study of 4984 critically ill children (age 0-25 years) from 32 PICUs. The validation of the ABC equations uses a subset of this cohort (n=2451) with a known Crb which serves as the gold standard, using statistical measures of accuracy and precision. The entire cohort is used for assessing changes in AKI epidemiology for different Crb estimating equations (3 ABC equations and 4 common eGFR equations). Univariate statistics determine how different Crb equations impact the incidence of AKI and its association with key clinical outcomes including 28-day mortality.

Results

The simplified ABC equation (requiring only age) performed similarly to existing Crb equations (e.g., new Schwartz). When an admission hospital creatinine value was available, the ABC equations outperformed all existing equations up to 19% in accuracy and 32% in precision. AKI incidence varied from 2-10% depending on Crb definition. Adverse clinical outcomes were rare: 28-day mortality (n=169) was 3.4% and ICU length of stay>=14 days (n=147) was 2.9%. Compared to previous Crb equations, ABC equations consistently perform better (or similar) to predict poor clinical outcomes. For example, relative risk (RR) of AKI using the ABC equation for 28-day mortality was 4.5 (95% CI 2.8-7.2); this was 5-29% higher RR than AKI defined by other Crb equations.

Conclusion

ABC equations outperform existing Crb estimating equations. This international cohort confirms earlier findings that ABC equations are improved methods for estimating Crb values. The data suggest ABC equations performed similarly, or perhaps better, in predicting select poor clinical outcomes.