Utility of Furosemide Stress Test (FST) in Predicting Progression of Acute Kidney Injury and Need for Renal Replacement Therapy in Critically Ill Patients

Introduction: Acute kidney injury (AKI) is a leading cause of morbidity and mortality in critically ill and its progression invokes substantial resource utilisation. Both early preemptive renal replacement therapy (RRT) and late reactive RRT worsen outcomes. Availability of a bedside tool to predict the need for RRT will help tailor the care of patients with AKI better. Our objective was to evaluate the ability of the Furosemide Stress Test (FST) in predicting the progression of AKI and requirement of RRT within a week. Material and Methods: Participants included were critically ill adults with Acute Kidney Injury Network (AKIN) Stage 1 and 2 kidney injury, admitted in a tertiary-level multidisciplinary critical care unit. The two-hour urine output of more than 200 ml was considered a positive response after a single weight-based dose of furosemide (1 or 1.5 mg/kg in the presence of prior exposure). Results: After screening 118 patients, FST was performed in 75 critically ill patients who met the inclusion criteria. By the end of the first week, 27 patients out of the 30 non-responders and five patients out of the 45 responders had progression of AKI. Analysis showed negative FST to have 90% positive predictive value (PPV), 88.9% negative predictive value (NPV) with a significant P value (<.01) and an area under the receiver operator characteristic (ROC) curve of 0.896 in predicting progression of AKI. At the end of seven days, 25 patients among the 30 non-responders, and four patients out of the 45 FST responders, ended up requiring RRT. Analysis showed negative FST to have 83.3% PPV, 89.1% NPV with a significant P value (<.01) and an area under the ROC curve of 0.888 in predicting the requirement of RRT at the end of one week. Conclusion: FST is an effective clinical tool for predicting AKI progression, the need for RRT in critically ill patients and can guide decision-making regarding initiation of RRT.