The role of flow-to-diameter ratio in predicting arteriovenous fistula complications in hemodialysis

Introduction: Arteriovenous fistulas (AVFs) are the preferred vascular access for hemodialysis but are prone to complications such as thrombosis, aneurysm, steal syndrome, and high-output heart failure. The Flow-to-Diameter Ratio (FDR), which integrates blood flow and vessel diameter, is a novel hemodynamic metric for AVF surveillance. This study evaluates FDR’s association with AVF complications in hemodialysis patients. Methods: This retrospective cohort study included 122 patients with radial-cephalic or brachial arteriovenous fistulas (AVFs) who had been on dialysis for ⩾5 years. Data for these patients were collected between January 2022 and January 2024. Doppler ultrasound was used to measure blood flow and vessel diameter to calculate the FDR (mL/min/mm). Patients were categorized into low (<100), normal (100–300), and high (>300) FDR groups. Complications were identified according to the KDOQI guidelines. Multivariate logistic regression and ROC curve analyses were used to assess FDR’s predictive value of the FDR. Results: The mean age was 64.5 ± 11.8 years, and 58% had radial-cephalic AVFs. A high FDR (>300 mL/min/mm) was associated with a 50% complication rate in both AVF types, compared to 17% (radial-cephalic) and 18% (brachial) in the normal FDR group. Low FDR (<100 mL/min/mm) showed moderate complication rates (29% radial-cephalic, 22% brachial). High FDR independently predicted complications (radial-cephalic: OR: 2.38, p = 0.015; brachial: OR: 2.51, p = 0.013). ROC analysis showed AUCs of 0.82 (radial-cephalic) and 0.86 (brachial) at an FDR cutoff of 305 mL/min/mm. Conclusion: The FDR is a robust predictor of AVF complications, with high values indicating an increased risk. Integrating FDR into Doppler surveillance may enhance risk stratification and guide timely intervention.