Predicting a strongly positive fluid balance in critically ill patients with acute kidney injury: A multicentre, international study.

Summary

An EMR-derived AKI-FB score using routinely available variables predicted >2 L positive fluid balance within 72 hours of AKI diagnosis with AUC 0.805 (external AUC 0.761). Key predictors included sepsis/septic shock, creatinine, cumulative fluid input, vasopressor use/dose, lactate, transfusion, and nutrition.

Key Findings

• Developed the AKI-FB risk score in 32,030 ICU patients; validated in 4,465 external patients.
• Threshold score of 32 predicted >2 L positive fluid balance at 72 h with 75% sensitivity and 72% specificity (AUC 0.805; external AUC 0.761).
• Sepsis/septic shock, highest creatinine, cumulative fluid balance, mechanical ventilation, noradrenaline use/dose, lactate ≥2 mmol/L, transfusion, and nutrition were key variables.

Clinical Implications

Supports early de-resuscitation strategies (diuretics, RRT, vasopressor-guided fluids) in high-risk AKI patients; can be embedded in EMRs to trigger alerts and guide fluid management protocols.

Limitations

• Observational model without prospective interventional testing or outcome improvement demonstration
• Generalizability beyond the contributing health systems and calibration across diverse ICUs require further study

Future Directions

Prospective implementation trials to test clinical impact on fluid balance, AKI progression, and mortality; integration with decision support for fluid de-escalation protocols.