The impact of access blood flow surveillance on reduction of thrombosis in native arteriovenous fistula: a randomized clinical trial

Purpose: The usefulness of access blood flow (Q(A)) measurement is an ongoing controversy. Although all vascular access (VA) clinical guidelines recommend monitoring and surveillance protocols to prevent VA thrombosis, randomized clinical trials (RCTs) have failed to consistently show the benefits of Q(A)-based surveillance protocols. We present a 3-year follow-up multicenter, prospective, open-label, controlled RCT, to evaluate the usefulness of Q(A) measurement using Doppler ultrasound (DU) and ultrasound dilution method (UDM), in a prevalent hemodialysis population with native arteriovenous fistula (AVF). Methods: Classical monitoring and surveillance methods are applied in all patients, the control group (n = 98) and the Q(A) group (n = 98). Besides this, DU and UDM are performed in the Q(A) group every three months. When Q(A) is under 500 ml/min or there is a >25% decrease in Q(A) the patient goes for fistulography, surgery or close clinical/surveillance observation. Thrombosis rate, assisted primary patency rate, primary patency rate and secondary patency rate are measured. Results: After one-year follow-up we found a significant reduction in thrombosis rate (0.022 thrombosis/patient/ year at risk in the Q(A) group compared to 0.099 thrombosis/patient/year at risk in the control group [p = 0.030]). Assisted primary patency rate was significantly higher in the Q(A) group than in control AVF (hazard ratio [HR] 0.23, 95% confidence interval [CI] 0.05-0.99; p = 0.030). In the Q(A) group, the numbers unddergoing angioplasty and surgery were higher but with no significant difference in non-assisted primary patency rate (HR 1.41, 95% CI 0.72-2.84; p = 0.293). There was a non-significant improvement in secondary patency rate in the Q(A) group (HR 0.510, 95% CI 0.17-1.50; p = 0.207). Conclusions: The measurement of Q(A) combining DU and UDM shows a reduction in thrombosis rate and an increased assisted primary patency rate in AVF after one-year follow-up.