Prognostic Value of the Diuretic Response to Low-Dose Furosemide for Predicting Progression from Acute Kidney Injury Stage 1 in Critically Ill Patients: A Retrospective Cohort Study.

PurposeThe furosemide stress test is useful for predicting acute kidney injury (AKI) progression, but its widespread use is limited by concerns regarding adverse events associated with high-dose administration (1-1.5 mg/kg). Furosemide responsiveness (FR) to lower doses seems to have high predictive value while reducing such risks, but its utility in early-stage AKI (stage 1) is unclear. We thus investigated the predictive value of FR in early-stage AKI.MethodsWe retrospectively reviewed adult intensive-care unit patients (≥18 years old) admitted between January 2021 and June 2024 who received a furosemide bolus dose during stage 1 of AKI. FR was assessed using the FR index (FRI; 2-h urine output per furosemide dose), body weight-adjusted FRI (mFRI), and body weight-adjusted 2-h urine output (UO/BW). The indices were compared by the Mann-Whitney U test between progression (stage ≥2 within 7 days) and non-progression groups, and predictive ability was assessed by a receiver operating characteristic (ROC) analysis.ResultsAmong 50 patients, 12 progressed and 38 did not. The mean furosemide dose was 0.29 mg/kg. FRI, mFRI, and UO/BW were significantly lower in the progression group (P < .001), with respective areas under the ROC curve of 0.945 (95% confidence interval, 0.887-1.000), 0.921 (0.831-1.000), and 0.919 (0.842-0.996). No hypotension requiring a rescue fluid bolus or other clinically overt hemodynamic instability was observed.ConclusionFR to lower doses was associated with subsequent progression from AKI stage 1 without evident hemodynamic instability in this cohort. These findings suggest that FR may provide a potentially safe and clinically useful indicator for early risk stratification in critically ill patients.