What question did this study set out to answer?

Investigate the predictive relationship between urine output trajectories during continuous renal replacement therapy and clinical outcomes in AKI patients.

March 26, 2026

790: Urine Output Trajectories in CRRT Predict Renal Recovery and Survival: A Retrospective Cohort Study

Key Points

Investigate the predictive relationship between urine output trajectories during continuous renal replacement therapy and clinical outcomes in AKI patients.
Analyzed data from 1,845 adult AKI patients receiving continuous renal replacement therapy from the MIMIC-IV database.
Stratified patients by urine output trajectories: recovery, stable, and anuria.
Utilized multivariable regression and Kaplan-Meier analyses to assess associations between urine output and clinical outcomes.
Outcomes measured included 28-day mortality, renal recovery, and ICU/hospital length of stay.
The recovery group had the lowest mortality and shortest ICU stay, while anuric patients had the worst outcomes.
Patients transitioning from oliguria/anuria to stable/recovered output exhibited better survival despite higher illness severity.
Survivors showed progressive urine output increases, whereas non-survivors had near-zero output.
Urine output recovery was confirmed as an independent predictor of renal function restoration with HR=0.709.
Identified protective factors included lower SOFA scores, lactate ≤2 mmol/L, and lower net ultrafiltration rate.

Abstract

Introduction: Acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT) presents significant challenges in prognostication and fluid management, as static biomarkers often fail to reflect dynamic renal recovery. While CRRT is lifesaving, predicting post-therapy outcomes remains elusive. Emerging evidence suggests that urine output trajectories during CRRT may serve as a dynamic marker for renal recovery and survival, yet this relationship remains underexplored. This study investigates whether urine output patterns during CRRT predict clinical outcomes, offering potential insights for personalized critical care. Methods: This retrospective cohort study analyzed 1,845 adult AKI patients receiving CRRT from the MIMIC-IV database. Patients were stratified by 24-hour post-CRRT urine output trajectories: recovery (≥50% increase), stable (< 50% change), and anuria (< 100 mL/24h). Outcomes included 28-day mortality, renal recovery, and ICU/hospital length of stay. Multivariable regression and Kaplan-Meier analyses assessed associations between urine output dynamics and clinical outcomes. Results: The recovery group exhibited the lowest mortality and shortest ICU stay, while anuric patients had the worst outcomes. Responders (transitioning from oliguria/anuria to stable/recovered output) had higher illness severity scores but better survival. Survivors demonstrated progressive urine output increases post-CRRT, whereas non-survivors maintained near-zero urine output. Logistic regression confirmed urine output recovery as an independent predictor of renal function restoration (HR=0.709, 95% CI=0.551–0.909, p=0.007). Optimal renal perfusion pressure (RPP=MAP-CVP) for urine output recovery ranged 50–60 mmHg. Subgroup analyses identified lower SOFA scores (< 8), lactate ≤2 mmol/L, and net ultrafiltration rate < 1 mL/kg/h as protective factors. Conclusions: Close monitoring of dynamic urine output trajectories during CRRT provides robust prognostic insights into renal recovery and survival, with early urine output improvement predicting favorable outcomes. Integrating real-time urine output kinetics with hemodynamic optimization enables personalized CRRT management, underscoring the potential of urine output trajectories-guided protocols to enhance AKI care, pending prospective validation.

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