Background: Observational studies indicate that routine measurements of access blood flow and use of Doppler ultrasound improve vascular access outcomes in hemodialysis patients, but randomized trials reached conflicting conclusions.
Study design: Systematic review and meta-analysis.
Setting & population: Adult hemodialysis patients with arteriovenous accesses.
Selection criteria for studies: Randomized trials.
Intervention: Screening with access blood flow measurements or Doppler ultrasound.
Outcomes: Thrombosis, access loss, and resource use.
Results: Of 1,613 identified citations and abstracts, 69 full articles were retrieved, and 12 randomized controlled trials comparing access screening (using access blood flow- or ultrasound-based screening) with standard care in a total of 1,164 participants were included. In meta-regression, vascular access type was significantly associated with the relative risk of thrombosis associated with screening (P < 0.01), supporting the need to stratify analyses on access type. In the 4 trials that studied arteriovenous fistulas, access blood flow- or ultrasound-based screening significantly decreased the risk of access thrombosis (relative risk [RR], 0.47; 95% confidence interval [CI], 0.28 to 0.77; 360 participants; I(2) = 8%), but not the risk of fistula loss (RR, 0.65; 95% CI, 0.28 to 1.51, I(2) = 0%) or resource use. Conversely, no decrease in risk of thrombosis (RR, 0.94; 95% CI, 0.77 to 1.16; 446 participants; I(2) = 0%) or access loss (RR, 1.08; 95% CI, 0.83 to 1.40; I(2) = 0%) was identified in trials studying grafts.
Limitations: Overall trial quality was moderate to poor, many trials did not report all clinically or economically relevant outcomes, and statistical power generally was low.
Conclusions: There was no evidence that screening with access blood flow measurements or Doppler ultrasound is of benefit to patients with grafts. Access blood flow screening may prevent access thrombosis in arteriovenous fistulas, but may not reduce the risk of access loss or extent of resource use. These findings have implications for clinical practice guidelines and for future research.