Flow Dysfunction of Hemodialysis Vascular Access

Maastricht University Medical Center375 enrolled

Overview

The FLOW trial evaluates the follow-up of the vascular access for hemodialysis. In current clinical care, vascular access flow volume is periodically assessed to detect and treat asymptomatic stenosis. The FLOW trial will determine whether it is safe to abandon this practice of active surveillance. Vascular access stenosis will then be treated only when clinical problems of flow dysfunction occur during hemodialysis. The investigators expect that the intervention rate and medical costs will be reduced by 40% when correction of vascular access stenosis is triggered by clinically apparent access dysfunction rather than asymptomatic flow reduction.

Study design: Multicenter randomized controlled trial with 375 patients. Patients will be followed up for 2 to 3 years. The trial is powered to detect a reduction in the intervention rate of 0.25 per year between study groups in a superiority analysis (this is associated with cost savings of 1 million euros per year in the Netherlands). Subgroup analyses of arteriovenous fistulas and grafts and of successful and failed interventions will be done. On 25-02-2025, the sample size was reduced from 417 to 375 patients because updated calculations based on actual event and loss to follow-up rates in the trial population showed sufficient power to detect the prespecified clinically relevant difference. Study population: Chronic hemodialysis patients with a functioning arteriovenous fistula or graft. Intervention group: Patients are referred for correction of the underlying stenosis when clinical signs of flow dysfunction are present. These include physical signs, problems during dialysis, or an unexplained, sustained fall in dialysis adequacy. Control group: Monthly surveillance of vascular access blood flow volume by ultrasound dilution measurements during hemodialysis sessions. Patients will be referred for correction of the underlying stenosis at an access flow volume \<500mL/min, or when clinical signs of flow dysfunction are present.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

Interventions

Vascular access monitoringDIAGNOSTIC_TEST

Patients are referred for correction of the underlying stenosis when clinical signs of flow dysfunction are present. These include physical signs, problems during dialysis, or an unexplained, sustained fall in dialysis adequacy. Patients will be referred for correction of the underlying stenosis when clinical signs of flow dysfunction are present.

Vascular access blood flow measurementDIAGNOSTIC_TEST

Monthly surveillance of vascular access blood flow volume by ultrasound dilution measurements during hemodialysis sessions. Patients will be referred for correction of the underlying stenosis at an access flow volume \<500mL/min.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Adult patients aged 18 years or older. 2. End-stage renal disease with unlikely recovery of kidney function according to the attending nephrologist. 3. Arteriovenous fistula or arteriovenous graft as hemodialysis vascular access that fulfills both of the following criteria at the time of trial enrollment: 1. Vascular access flow volume of at least 500mL/min; and 2. Functional vascular access: the vascular access was cannulated with 2 needles and achieved the prescribed access circuit flow in at least 6 dialysis sessions over the past 30 days. Patients who have single needle hemodialysis for reasons other than vascular access dysfunction (e.g. for nocturnal hemodialysis) but who can be cannulated with 2 needles for flow measurements and fulfill the other requirements for a functional vascular access can be enrolled as well. 4. Planning to remain in one of the participating dialysis centers for at least 1 year. Exclusion Criteria: 1. Arteriovenous fistulas with multiple venous outflow paths upstream of the cannulation sites, that are not suitable for flow volume measurements using ultrasound dilution (e.g. Gracz fistulas and Ellipsys or WavelinQ endovascular fistulas). 2. Home hemodialysis. 3. Thrombosis of the current vascular access in the past year. 4. Planned access-related intervention. 5. Living donor kidney transplantation, switch to peritoneal dialysis, or switch to home hemodialysis planned within 6 months. 6. Life expectancy of less than 6 months, in the opinion of the attending nephrologist. 7. Unable to provide informed consent.

Locations (13)

Diapriva - Dialyse Centrum Amsterdam

Amsterdam, Netherlands

OLVG

Amsterdam, Netherlands

Deventer Ziekenhuis

Deventer, Netherlands

Medisch Spectrum Twente

Enschede, Netherlands

Spaarne Gasthuis

Haarlem, Netherlands

Zuyderland Medisch Centrum

Heerlen, Netherlands

Leids Universitair Medisch Centrum

Leiden, Netherlands

Maastricht UMC+

Maastricht, Netherlands

Bravis Ziekenhuis

Roosendaal, Netherlands

Franciscus Gasthuis & Vlietland

Rotterdam, Netherlands

...and 3 more locations

Outcomes

Primary Outcomes

Access-related intervention rate

The number of interventions required for each patient-year of hemodialysis treatment

Time frame: Variable follow-up time of 2-3 years

Secondary Outcomes

Access-related complications per patient-year (1)

Clavien-Dindo grade 2 complications (requiring pharmacological treatment)

Time frame: Variable follow-up time of 2-3 years

Access-related complications per patient-year (2)

Access-related serious adverse events (Clavien-Dindo grade 4 and 5 complications, and vascular access thrombosis)

Time frame: Variable follow-up time of 2-3 years

All-cause mortality

Time frame: Variable follow-up time of 2-3 years

Access-related health care costs (1)

Medical Consumption Questionnaire

Time frame: Every 3 months for 2-3 years from randomization (variable follow-up time)

Access-related health care costs (2)

Productivity Cost Questionnaire

Time frame: Every 3 months for 2-3 years from randomization (variable follow-up time)

Patient-reported outcome measures (1)

SF-VAQ (Short-Form Vascular Access Questionnaire)

Time frame: Every 3 months for 2-3 years from randomization (variable follow-up time)

Patient-reported outcome measures (2)

EQ-5D-5L

Time frame: Every 3 months for 2-3 years from randomization (variable follow-up time)

Quality of the surveillance program (1)

Repeatability and reproducibility of vascular access flow volume measurements

Time frame: Variable follow-up time of 2-3 years

Quality of the surveillance program (2)

Diagnostic accuracy of vascular access flow volume measurements to predict clinical signs of flow dysfunction and access thrombosis within 1 month in the intervention group

Time frame: Variable follow-up time of 2-3 years

Quality of the surveillance program (3)

The percentage of vascular access balloon angioplasties resulting in technical success (residual stenosis \<30%) and clinical success (increase in flow volume to \>500mL/min, restoration of vascular access function and resolution of any clinical signs of flow dysfunction)

Time frame: Variable follow-up time of 2-3 years

Quality of the surveillance program (4)

Vascular access patency after balloon angioplasty

Time frame: Variable follow-up time of 2-3 years

Primary patency

This outcome measure will be registered for explanatory analyses

Time frame: Variable follow-up time of 2-3 years

Assisted primary patency

This outcome measure will be registered for explanatory analyses

Time frame: Variable follow-up time of 2-3 years

Secondary patency

This outcome measure will be registered for explanatory analyses

Time frame: Variable follow-up time of 2-3 years

The number of hemodialysis sessions with cannulation difficulties

This outcome measure will be registered for explanatory analyses

Time frame: Variable follow-up time of 2-3 years

Flow Dysfunction of Hemodialysis Vascular Access

Overview

Conditions

Interventions

Eligibility

Locations (13)

Outcomes

Primary Outcomes

Secondary Outcomes