Pro: Vascular access surveillance in mature fistulas: is it worthwhile?

Abstract Guidelines recommend regular screening of mature arteriovenous fistulas (AVFs) for preemptive repair of significant stenosis (≥50% lumen reduction) at high risk of thrombosis, identifiable from clinical signs of access dysfunction (monitoring) or by measuring access blood flow (Qa surveillance), which also enables stenosis detection in functional accesses. To compare the value of Qa surveillance versus monitoring, a meta-analysis was performed on the randomized controlled trials (RCTs) comparing the two screening strategies. It emerged that correcting stenosis identified by Qa surveillance significantly halved the risk of thrombosis [relative risk (RR) = 0.51, 95% confidence interval (CI) 0.35–0.73] and access loss (RR = 0.47, 95% CI 0.28–0.80) in comparison with intervention prompted by clinical signs of access dysfunction. One small RCT aiming to identify an optimal Qa threshold showed that stenosis repair at Qa >500 mL/min produced a significant 3-fold reduction in the risk of thrombosis (RR = 0.37, 95% CI 0.12–0.97) and access loss (RR = 0.36, 95% CI 0.09–0.99) in comparison with intervening when Qa dropped to 500 mL/min was considered (2.4, 95% CI 1.0–4.6 and 2.2, 95% CI 0.7–5.0 versus 9.4, 95% CI 7.4–11.3 and 10.3, 95% CI 7.7–13.4 events per 100 AVFs-year, P ≤ 0.024), suggesting that in clinical practice adopting Qa surveillance may only be worthwhile at centres with high thrombosis and access loss rates associated with monitoring, and adopting Qa thresholds >500 mL/min for elective stenosis repair.