title: Does monthly native arteriovenous fistula blood-flow surveillance detect significant stenosis--a randomized controlled trial.
abstract: BACKGROUND
  Clinical practice guidelines recommend that the preferred method of surveillance for arteriovenous fistula (AVF) is the measurement of AVF blood flow (Qa). As these recommendations are based on observational studies, we conducted a randomized, prospective, double-blind, controlled trial to assess whether Qa surveillance results in an increased detection of AVF stenosis.
  
  
  METHODS
  A total of 137 patients were randomly assigned to receive either continuing AVF surveillance using current clinical criteria (control, usual treatment) or usual treatment plus AVF blood-flow surveillance by ultrasound dilution (Qa surveillance group). The primary outcome measure was the detection of a significant (>50%) AVF stenosis.
  
  
  RESULTS
  There were 67 and 68 patients assigned to the control and Qa surveillance groups, respectively. Patients in the Qa surveillance group were twice as likely to have a stenosis detected compared with the control hazard ratio (HR) confidence interval (CI) group (2.27, 95% 0.85-5.98, P = 0.09), with a trend for a significant stenosis to be detected earlier in the Qa surveillance group (P = 0.09, log rank test). However, using the Qa results alone prior to angiography, the area under the receiver operating characteristic curve demonstrated, at best, a moderate prediction of (>50%) AVF stenosis (0.78, 95% CI 0.63-0.94, P = 0.006).
  
  
  CONCLUSIONS
  This study demonstrates that the addition of AVF Qa monitoring to clinical screening for AVF stenosis resulted in a non-significant doubling in the detection of angiographically significant AVF stenosis. Further, large multi-centre randomized trials are feasible and will be necessary to confirm whether Qa surveillance and the correction of detected AVF stenosis will lead to a reduction in AVF thrombosis and increased AVF survival.
authors.affiliation: Department of Nephrology, Monash Medical Centre, 246 Clayton Rd, Clayton, Melbourne, Victoria 3168, Australia. kevan.polkinghorne@med.monash.edu.au
authors.forename: Kevan R
authors.initials: KR
authors.lastname: Polkinghorne
authors.forename: Kenneth K P
authors.initials: KK
authors.lastname: Lau
authors.forename: Alan
authors.initials: A
authors.lastname: Saunder
authors.forename: Robert C
authors.initials: RC
authors.lastname: Atkins
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kerr
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction; D001166:Arteriovenous Shunt, Surgical; D001783:Blood Flow Velocity / Q000502:physiology*; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007676:Kidney Failure, Chronic / Q000000981:diagnostic imaging / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D006435:Renal Dialysis / Q000379:methods*; D013997:Time Factors; D014463:Ultrasonography