Association Between the Modified Furosemide Response Index and Prognosis in Patients with Chronic Kidney Disease: A Retrospective Cohort Study Based on the MIMIC-IV Database

Zhibin Chen,1,* Guobao Hong,2,* Hua Xiao,2 Qiaobin Wu,1 Kai Liu11Department of Emergency, The Affiliated Shunde Hospital of Jinan University, Foshan, Guangdong, People’s Republic of China; 2Department of Nephrology, The Affiliated Shunde Hospital of Jinan University, Foshan, Guangdong, People’s Republic of China*These authors contributed equally to this workCorrespondence: Qiaobin Wu, Department of Emergency, The Affiliated Shunde Hospital of Jinan University, Foshan, Guangdong, People’s Republic of China, Email 65173173@qq.com Kai Liu, Department of Emergency, The Affiliated Shunde Hospital of Jinan University, Foshan, Guangdong, People’s Republic of China, Email 1046137886@qq.comBackground: The modified furosemide response index (mFRI), derived from a standardized furosemide stress test, is a biomarker of diuretic responsiveness and AKI progression. Its prognostic value in chronic kidney disease (CKD) remains unclear. This study examined the association between mFRI and clinical outcomes in critically ill patients with CKD.Methods: We conducted a retrospective cohort study using the MIMIC‑IV database. Critically ill CKD patients receiving furosemide were included. Restricted cubic splines were used to examine the non‑linear relationship between mFRI and mortality. Patients were grouped by mFRI quartiles. Multivariable Cox and logistic regression assessed outcome associations, with subgroup analyses for robustness.Results: Among 3,311 patients, a significant L‑shaped non‑linear association was observed between mFRI and 28‑day mortality (P