The "Rule of 4" ultrasound diagnostic criteria at 6 weeks postoperatively was more appropriate for clinical determination of arteriovenous fistula maturation.

Objective: investigate the timing of assessing the maturation of arteriovenous fistula (AVF) and the diagnostic efficacy of two ultrasound assessment criteria in determining the maturation of AVF.

Methods: We collected clinical data on 227 patients with end-stage renal disease who were first diagnosed at our institution between February 1, 2023 and February 1, 2024, and were followed up regularly for 12 weeks post-AVF creation, with the diameter of the draining vein and the brachial artery volume flow (VF) recorded at 1 day, 2, 4, 6, 8, 10, and 12 weeks post-operation. We focused on the time of AVF maturation, and ultrasonographic diagnostic criteria 1 (the vein diameter was ≥4 mm, and the brachial artery VF was >500 mL/min, referred to as the "Rule of 4") and ultrasonographic diagnostic criteria 2 (the vein diameter was ≥5 mm, and the brachial artery VF was> 500 mL/min, referred to as the "Rule of 5") were used to evaluate the maturation of AVF. And compared with clinically maturation criteria to understand the correlation, consistency, and diagnostic efficacy.

Results: 1. The venous diameter and brachial artery VF of AVF showed an upward trend, and increased significantly in 1 day to 6 weeks postoperatively ( < .05),especially between 1 day and 2 weeks, while no significant difference in the increases at 6-12 weeks; 2. Logistic regression analysis showed that venous diameter (OR = 19.589 , 95% CI 1.560-245.979, = .021) and brachial artery VF (OR = 1.024 , 95% CI 1.005-1.042, = .011) at 6 weeks were the independent correlates affecting AVF maturation; and the optimal thresholds were 4.08 mm (sensitivity 88.10%, specificity 70.00%) and 472.50 mL/min (sensitivity 93.20%, specificity 84.00%), respectively; 3. Compared with clinical maturation, the two ultrasonographic diagnostic criteria at 6 weeks postoperatively were correlated with clinical maturation, and the specificity of both was 100%, with "Rule of 4" having a sensitivity of 79.66%, an accuracy of 84.14%, and a concordance kappa = 0.633, while "Rule of 5″ had a sensitivity of 31.63%, an accuracy of 46.69%, and a concordance kappa = 0.169; and the area under the ROC curve (AUC) for "Rule of 4″ was higher than that for "Rule of 5" (0.898 vs. 0.658, < .001).

Conclusion: Six weeks postoperatively may be the best timing for an ultrasound assessment of AVF maturation, and the "Rule of 4" ultrasound assessment criteria was more suitable for clinical judgment of AVF maturation.