title: The impact of access blood flow surveillance on reduction of thrombosis in native arteriovenous fistula: a randomized clinical trial.
abstract: OBJECTIVE
  The usefulness of access blood flow (QA) 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 QA-based surveillance protocols. We present a 3-year follow-up multicenter, prospective, open-label, controlled RCT, to evaluate the usefulness of QA 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 QA group (n = 98). Besides this, DU and UDM are performed in the QA group every three months. When QA is under 500 ml/min or there is a >25% decrease in QA 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 QA 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 QA group than in control AVF (hazard ratio [HR] 0.23, 95% confidence interval [CI] 0.05-0.99; p = 0.030). In the QA 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 QA group (HR 0.510, 95% CI 0.17-1.50; p = 0.207).
  
  
  CONCLUSIONS
  The measurement of QA combining DU and UDM shows a reduction in thrombosis rate and an increased assisted primary patency rate in AVF after one-year follow-up.
  
  
  BACKGROUND
  ClinicalTrials.gov Identifier: NCT02111655.
authors.affiliation: Nephrology Unit, Hospital Infanta Sofía, Madrid - Spain.|Clínica Fuensanta, Hemodialysis Unit, Madrid - Spain.
authors.forename: Inés
authors.initials: I
authors.lastname: Aragoncillo
authors.affiliation: Clínica Fuensanta, Hemodialysis Unit, Madrid - Spain.
authors.forename: Yésika
authors.initials: Y
authors.lastname: Amézquita
authors.affiliation: Nephrology Unit, Hospital Infanta Sofía, Madrid - Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Caldés
authors.affiliation: Nephrology Unit, Hospital Gregorio Marañón, Madrid - Spain.
authors.forename: Soraya
authors.initials: S
authors.lastname: Abad
authors.affiliation: Nephrology Unit, Hospital Gregorio Marañón, Madrid - Spain.
authors.forename: Almudena
authors.initials: A
authors.lastname: Vega
authors.affiliation: Nephrology Unit, Hospital Infanta Sofía, Madrid - Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Cirugeda
authors.affiliation: Clínica Fuensanta, Hemodialysis Unit, Madrid - Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Moratilla
authors.affiliation: Corporació Sanitària i Universitària Parc Taulí, Hospital de Sabadell, Barcelona - Spain.
authors.forename: José
authors.initials: J
authors.lastname: Ibeas
authors.affiliation: Nephrology Unit, Hospital de Mollet, Mollet del Vallès, Barcelona - Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Roca-Tey
authors.affiliation: Preventive Medicine Unit, Hospital Clínico, Madrid - Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Fernández
authors.affiliation: Nephrology Unit, Hospital Gregorio Marañón, Madrid - Spain.
authors.forename: Borja
authors.initials: B
authors.lastname: Quiroga
authors.affiliation: Clínica Dialcentro, Hemodialysis Unit, Madrid - Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Blanco
authors.affiliation: Clínica Dialcentro, Hemodialysis Unit, Madrid - Spain.
authors.forename: Maite
authors.initials: M
authors.lastname: Villaverde
authors.affiliation: Clínica Dialcentro, Hemodialysis Unit, Madrid - Spain.
authors.forename: Caridad
authors.initials: C
authors.lastname: Ruiz
authors.affiliation: Clínica Los Enebros, Hemodialysis Unit, Madrid - Spain.
authors.forename: Belén
authors.initials: B
authors.lastname: Martín
authors.affiliation: Clínica Los Enebros, Hemodialysis Unit, Madrid - Spain.
authors.forename: Asunción M
authors.initials: AM
authors.lastname: Ruiz
authors.affiliation: Clínica Los Enebros, Hemodialysis Unit, Madrid - Spain.
authors.forename: Jara
authors.initials: J
authors.lastname: Ampuero
authors.affiliation: Nephrology Unit, Hospital Gregorio Marañón, Madrid - Spain.
authors.forename: Juan M
authors.initials: JM
authors.lastname: López-Gómez
authors.affiliation: Nephrology Unit, Hospital Infanta Sofía, Madrid - Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: de Alvaro
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects*; D001783:Blood Flow Velocity; D005260:Female; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012039:Regional Blood Flow; D006435:Renal Dialysis; D012307:Risk Factors; D013030:Spain; D013927:Thrombosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D013997:Time Factors; D016896:Treatment Outcome; D018608:Ultrasonography, Doppler; D014654:Vascular Patency