FLOW

The FLOW project 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 project 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.

We expect that the access-related 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 by asymptomatic flow reduction detected by surveillance. This would amount to cost savings of 3.0 million euros per year in the Netherlands.
We expect that the rate of access thrombosis will increase no more than 0.5 events per patient-year when correction of vascular access stenosis is triggered by clinically apparent access dysfunction rather than by asymptomatic flow reduction detected by surveillance.

Patients will be followed up for 2 years for the primary outcome and secondary outcomes. Access-related interventions and complications will be registered prospectively during this time period. Medical costs and patient-reported outcomes will be measured with questionnaires every 3 months. The quality of the surveillance program will be evaluated using data accumulated over the 2-year study period.

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.
Comparison 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.