Abstract
Background: The relationship between urine output (UO) and severe-stage progression in the early phase of acute kidney injury (AKI) remains unclear. This study aimed to investigate the relationship between early-phase UO6−12h [UO within 6 h after diagnosis of stage 1 AKI by Kidney Disease: Improving Global Outcomes (KDIGO) UO criteria] and severe-stage progression of AKI and to identify a reference value of early-phase UO6−12h for guiding initial therapy in critical care.Methods: Adult patients with UO < 0.5 ml/kg/h for the first 6 h after intensive care unit (ICU) admission (meeting stage 1 AKI by UO) and UO6−12h ≥ 0.5 ml/kg/h were identified from the Medical Information Mart for Intensive Care (MIMIC) III database. The primary outcome was progression to stage 2/3 AKI by UO. After other variables were adjusted through multivariate analysis, generalized additive model (GAM) was used to visualize the relationship between early-phase UO6−12h and progression to stage 2/3 AKI by UO. A two-piecewise linear regression model was employed to identify the inflection point of early-phase UO6−12h above which progression risk significantly leveled off. Sensitivity and subgroup analyses were performed to assess the robustness of our findings.Results: Of 2,984 individuals, 1,870 (62.7%) with KDIGO stage 1 UO criteria progressed to stage 2/3 AKI. In the multivariate analysis, early-phase UO6−12h showed a significant association with progression to stage 2/3 AKI by UO (odds ratio, 0.40; 95% confidence interval, 0.34–0.46; p < 0.001). There was a non-linear relationship between early-phase UO6−12h and progression of AKI. Early-phase UO6−12h of 1.1 ml/kg/h was identified as the inflection point, above which progression risk significantly leveled off (p = 0.780). Patients with early-phase UO6−12h ≥ 1.1 ml/kg/h had significantly shorter length of ICU stay (3.82 vs. 4.17 days, p < 0.001) and hospital stay (9.28 vs. 10.43 days, p < 0.001) and lower 30-day mortality (11.05 vs. 18.42%, p < 0.001). The robustness of our findings was confirmed by sensitivity and subgroup analyses.Conclusions: Among early-stage AKI patients in critical care, there was a non-linear relationship between early-phase UO6−12h and progression of AKI. Early-phase UO6−12h of 1.1 ml/kg/h was the inflection point above which progression risk significantly leveled off.
Highlights
Acute kidney injury (AKI) is common in the intensive care unit (ICU), and mortality dramatically increases as the severerstage progression of AKI in critical patients [1,2,3]
The therapeutic window of AKI could become narrower as kidney function worsens, and early improvement in the early phase of AKI is of importance for improving outcome [8,9,10]
It has been shown that a number of earlystage AKI patients still suffered from progression to severer stage, even though their urine output (UO) was above 0.5 ml/kg/h in the early phase of therapy [1]
Summary
Acute kidney injury (AKI) is common in the intensive care unit (ICU), and mortality dramatically increases as the severerstage progression of AKI in critical patients [1,2,3]. The latest update of the Surviving Sepsis Campaign guideline does not mention a specific initial therapy goal for UO [11], which was once recommended to be ≥0.5 ml/kg/h in the previous version of the guideline [12] This change indicates that 0.5 ml/kg/h might not be the optimal UO target for therapy in critical patients. This study aimed to investigate the relationship between early-phase UO6−12h [UO within 6 h after diagnosis of stage 1 AKI by Kidney Disease: Improving Global Outcomes (KDIGO) UO criteria] and severe-stage progression of AKI and to identify a reference value of early-phase UO6−12h for guiding initial therapy in critical care
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