Mortality, Renal Replacement Therapy and Renal Impairment Markers in Critically Ill Patients in a Multinational Point-Prevalence ICU Cohort over 2007 to 2024: A nutritionDay Descriptive Multivariable Analysis

Background: The study goal was to assess the association between mortality and renal impairment markers in the nutritionDay ICU cohort, incorporating creatinine, urine volume, and renal replacement therapy (RRT) while adjusting for ICU- and patient-level factors. Methods: During nutritionDay, participating ICUs worldwide prospectively documented all patients treated on a predefined study day in November. Renal impairment markers included creatinine and urine volume at ICU admission and RRT status on nutritionDay. ICU-level factors included world region, calendar year and time of assessment. Patient-level factors included sex, age, BMI, disease severity, and underlying disease leading to ICU admission. Sixty-day hospital mortality and use of RRT on nutritionDay were assessed in multivariable logistic regressions including all ICU- and patient-level factors. Results: The post hoc analysis included 23,485 adult ICU patients from 1855 ICU-year units in 60 countries from 2007 to 2024, with analytic sample sizes of 23,485 for RRT, 18,245 for mortality, 21,054 for creatinine, and 20,753 for urine volume. Mean age was 61.4 (SD 17.0) years. Mean SAPS 2 at ICU admission was 39.8 (SD 17.7) points. Renal replacement therapy was associated with approximately twice the observed mortality. Severity of illness remained a major determinant of mortality after removing age and urine volume from SAPS 2. RRT use was similar up to 70 years but declined thereafter. Creatinine increased with age and BMI, while urine volume progressively declined with age. The reason for ICU dependency was associated with mortality, RRT use, creatinine, and urine volume. Conclusions: RRT, age and severity of illness were strongly associated with mortality in this large ICU cohort. The reason for ICU dependency, reflecting the underlying disease, was substantially associated with mortality, RRT use, creatinine, and urine volume.