Adding access blood flow surveillance to clinical monitoring reduces thrombosis rates and costs, and improves fistula patency in the short term: a controlled cohort study.

BACKGROUND: Access blood flow (Qa) measurement is the recommended method for fistula (AVF) surveillance for stenosis, but whether it may be beneficial and cost-effective is controversial. METHODS: We conducted a 5-year controlled cohort study to evaluate whether adding Qa surveillance to unsystematic clinical monitoring (combined with elective stenosis repair) reduces thrombosis and access loss rates, and costs in mature AVFs. We prospectively collected data in 159 haemodialysis patients with mature AVFs, 97 followed by unsystematic clinical monitoring (Control) and 62 by adding Qa surveillance to monitoring (Flow). Indications for imaging and stenosis repair were clinically evident access dysfunction in both groups and a Qa < 750 ml/min or dropping by >20% in Flow. RESULTS: Adding Qa surveillance prompted an increase in access imaging (HR 2.96, 95% CI 1.79-4.91, P < 0.001), stenosis detection (HR 2.55, 95% CI 1.48-4.42, P = 0.001) and elective repair (HR 2.26, 95% CI 1.16-4.43, P = 0.017), and a reduction in thromboses (HR 0.27, 95% CI 0.09-0.79, P = 0.017), central venous catheter placements (HR 0.14, 95% CI 0.03-0.42, P = 0.010) and access losses (HR 0.35, 95% CI 0.11-1.09, P = 0.071). In the Kaplan-Meier analysis, adding Qa surveillance only extended short-term cumulative patency (P = 0.037 in the Breslow test). Mean access-related costs were 1213 Euro/AVF-year in Control and 743 in Flow (P < 0.001). CONCLUSIONS: Our controlled cohort study shows that adding Qa surveillance to monitoring in mature AVFs is associated with a better detection and elective treatment of stenosis, and lower thrombosis rates and access-related costs, although the cumulative access patency was only extended in the first 3 years after fistula maturation. We are aware of the limitations of our study (non-randomization and the possible centre effect) and that further, better-designed trials are needed to arrive at a definitive answer concerning the role of Qa surveillance for fistulae.