Risk Stratification by eGFR < 45 mL /min/1.73 m 2 for All‐Cause Mortality in Patients With Diabetic Foot Ulcer: A Multidisciplinary Retrospective Cohort Study

ABSTRACT Aims Patients with diabetic foot ulcer (DFU) complicated by chronic kidney disease (CKD) have poor survival, yet nonlinear prognostic evidence of estimated glomerular filtration rate (eGFR) in this population remains limited. This study aimed to characterize the eGFR‐all‐cause mortality association in a multidisciplinary‐managed DFU cohort. Material and Methods In this retrospective cohort, 595 hospitalized DFU patients were enrolled. Restricted cubic spline (RCS), Kaplan–Meier, and multivariable Cox regression were applied to assess survival and independent predictors. Sensitivity and subgroup analyses were performed to confirm result robustness. Results A significant nonlinear eGFR‐mortality relationship was observed (P for nonlinearity < 0.001). Survival worsened markedly among patients with eGFR < 45 mL/min/1.73 m 2 (log‐rank p < 0.001). Relative to eGFR ≥ 60 mL/min/1.73 m 2 , adjusted HRs were 2.59 (95% CI: 1.34–4.98, p = 0.004) for eGFR 30–< 45 mL/min/1.73 m 2 and 4.67 (95% CI: 2.63–8.30, p < 0.001) for eGFR < 30 mL/min/1.73 m 2 . Advanced age, lower BMI and reduced serum albumin independently predicted mortality. Sensitivity analyses confirmed result robustness, while subgroup interaction analyses revealed minimal outcome heterogeneity apart from sex‐related effect modification. Conclusions DFU patients with eGFR < 45 mL/min/1.73 m 2 face substantially higher long‐term all‐cause mortality. Our findings support extending the “renal foot” phenotype to CKD Stage 3b and above. Routine eGFR evaluation aids early risk stratification and tailored multidisciplinary DFU‐directed clinical care.