Objectives: To investigate whether the urine output trajectory is associated with dialysis independence in critically ill children with acute kidney injury (AKI). Design: Retrospective cohort study. Setting: A PICU in Japan. Patients: Children younger than 16 years old who received continuous kidney replacement therapy (CKRT) for AKI between July 1, 2014, and June 30, 2023. Interventions: None. Measurements and Main Results: We identified 61 eligible patients, including 16 patients who remained dialysis-dependent 30 days after CKRT initiation. Compared with dialysis-independent patients, dialysis dependence was associated with lower urine output on days 3, 7, 14, and 21 after CKRT initiation. Dialysis independence, when compared with dialysis dependence, was associated with higher median (interquartile range) urine output (mL/kg/hr) at each timepoint (day 3: 0.3 0.1–1.6 vs. 0.0 0–0.2; p = 0.001; day 7: 1.3 0.4–2.0 vs. 0.0 0–0.1; p < 0.001; day 14: 1.8 1.0–3.5 vs. 0.0 0–0; p < 0.001; and day 21: 2.1 1.1–3.0 vs. 0.0 0–0; p < 0.001). The area under the receiver operating characteristic curve (AUROC with 95% CI) for identifying dialysis independence at day 30 after CKRT initiation, based on urine output on day 14, was 0.96 (95% CI, 0.88–1.00). Using the DeLong test, this AUROC was higher than that on day 7 (0.88 95% CI, 0.77–0.99; p = 0.009). Also, on day 14, with a pre-test probability of dialysis independence of 71%, the post-test probability increases to 97% when using a test urine output greater than or equal to 0.41 mL/kg/hr. The sensitivity analysis with the exclusion of neonates yielded similar results. Conclusions: In this 2014–2023 cohort of critically ill children with AKI supported with CKRT, using a urine output greater than or equal to 0.41 mL/kg/hr on day 14, CKRT may be an effective diagnostic test of dialysis independence on day 30. Further validation studies are needed.
Tokuda et al. (Mon,) studied this question.