Clinical Scorecard: Aligning Urine Output Thresholds for Acute Kidney Injury Stages With Creatinine-Based Mortality Risk
At a Glance
Category
Detail
Condition
Acute kidney injury (AKI), staged using KDIGO criteria
Key Mechanisms
The study compared urine-output thresholds with creatinine-defined KDIGO stages by matching their associations with 14-day mortality.
Target Population
Adults aged 18 years or older admitted to a general ICU, excluding patients with pre-existing chronic kidney disease.
Care Setting
Single tertiary-care general ICU at Uppsala University Hospital, Sweden; findings require validation in other ICU populations and healthcare systems.
Key Highlights
The analysis included 5,698 ICU admissions involving 4,999 unique adults.
Under current urine-output criteria, mortality was underestimated by 37% at stage 1 and 48% at stage 2, and overestimated by 34% at stage 3, relative to creatinine-defined staging.
Mortality-equivalent urine-output thresholds were identified for each creatinine-defined KDIGO stage over 3-, 6-, and 12-hour periods; for 24 hours, thresholds were identified for stages 1 and 2 but not stage 3.
All identified thresholds were below the current stage 1 cutoff of 0.5 mL/kg/h.
Urine output below 0.24 mL/kg/h sustained for 3 hours was associated with mortality equivalent to creatinine-defined stage 1 AKI.
Guideline-Based Recommendations
Diagnosis
KDIGO remains the standard definition and staging system for AKI; the proposed 2026 revision retains the existing urine-output criterion.
The study provides mortality-equivalent urine-output thresholds as reference values for future validation, not as established replacement diagnostic criteria.
Management
Monitoring & Follow-up
The analysis evaluated minimum average urine output across overlapping 3-, 6-, 12-, and 24-hour intervals.
Risks
Thresholds are prognostic rather than causal and were adjusted only for age and sex; residual confounding cannot be ruled out.
Diuretic administration, fluid status, and continuous renal replacement therapy were not considered.
The study was conducted in one tertiary-care ICU and requires validation in other healthcare systems and ICU populations.
Patient & Prescribing Data
Adults aged 18 years or older admitted to the general ICU at Uppsala University Hospital from October 6, 2015, through April 30, 2024; admissions involving pre-existing chronic kidney disease were excluded.
No treatment or prescribing intervention was evaluated. The study assessed associations between minimum sustained urine output and 14-day mortality.
Clinical Best Practices
Interpret the reported urine-output thresholds as prognostic research findings, not causal estimates or validated clinical cutoffs.
Consider the study's single-center setting and unmeasured factors affecting urine output when interpreting its thresholds.
Further validation in other ICU populations is required before the thresholds are used in clinical guidelines.
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