12-month follow-up of the surveillance of arteriovenous fistulae in haemodialysis (SONAR) study

Plain English Summary

Background and study aims
The kidneys are required for the excretion of excess fluid and harmful toxins. If a person develops kidney failure, then the build-up of toxins and fluid can be fatal within a few days. Consequently, patients with kidney failure require either a replacement kidney (kidney transplant) or for the excess fluid and toxins to be removed from the body by a process known as dialysis. Most patients who develop chronic kidney failure will need dialysis at some point. Two-thirds of patients with kidney failure (around 20,000 patients a year in the UK) receive regular dialysis through a machine (haemodialysis).

Haemodialysis involves attachment to the machine requires either the placement of semi-permanent 'lines' (plastic tubing) into one of the big veins in the patient's chest, or the surgical creation of an 'arterio-venous fistula', in which one of the small arteries in the arm is joined directly to one of the veins. The vein becomes gradually bigger allowing for a greater flow of blood. The fistula vein can then have two needles inserted into it to enable connection with the dialysis machine. The increased rate of blood flow within the fistula vein, coupled with the increased size and wall thickness of the vein, allow for successful, and repeated needling. Fistulas are the best option for most patients, as the risks of a life-threatening blood infection are about ten times less common than for patients who dialyse via their 'line'.

Unfortunately, the creation of an arterio-venous fistula is not an exact science and up to half of them fail within a year of being created, despite a successful join at the time of surgery. The reasons why this happens and how we can prevent it are largely unknown. Our study will examine whether we can use 'Doppler ultrasound' (a non-invasive scan that uses high-frequency sound waves to create a picture of the blood flow in the fistula) to identify early problems with a fistula that may lead to it failing.

To test whether ultrasound helps predict which fistulas will fail, this study will recruit patients who need to have a fistula created. The study team will perform a series of scans in the weeks after the operation but the results will not be shared with the patients or their clinicians. This should allow the study team to find out whether the scan helps to predict fistula failure or not, and when the best time is to perform the scan after the operation. If this study is able to show that ultrasound can be used to successfully identify fistulas that are not likely to mature, then the study team will proceed to undertake a second study. This second study will evaluate whether it is possible to intervene at an early stage in those fistulas that are identified by ultrasound as unlikely to mature, and by doing so improve the longevity of the fistula (patency). There is still a great deal of debate about the role of ultrasound in predicting the chances that a fistula will mature successfully. This is important because the use of ultrasound is expensive, but also means that patients have additional scans that may not be needed.

This study, which will involve a number of large UK dialysis centres, will show clearly how effective or otherwise ultrasound is at predicting whether fistulas develop successfully and whether this represents a good use of NHS funds. By doing so, it is anticipated that the study will influence current dialysis practices in the UK and abroad.

Who can participate?
Patients who took part in the Surveillance of arteriovenous fistulae using ultrasound (SONAR) study (isrctn.com/ISRCTN36033877) can participate in SONAR-12M

What does the study involve?
The study involves giving consent for the researchers to collect additional information from the medical records of participants. Data collected will be about the arteriovenous fistulae studied in the SONAR study, haemodialysis, kidney transplantation, and venous access surgeries or procedures. This data will be collected at 12 months after the fistula was created, and again at 5 years after the fistula was created. There are no additional hospital visits or tests involved.

What are the possible benefits and risks of participating?
There are no immediate benefits of participating, and no clinical risks as there are no tests, procedures, or study visits. All routine clinical care will continue. The researchers hope that the study may benefit kidney disease patients in the future.

Where is the study run from?
Cambridge University Hospitals NHS Foundation Trust (UK) and the University of Cambridge (UK). Clinical Trial Management, Data Management, and Statistics are provided by the NHS Blood and Transplant Clinical Trials Unit (UK).

When is the study starting and how long is it expected to run for?
From October 2020 to December 2025

Who is funding the study?
The National Institute for Health Research (UK)

Who is the main contact?
Gavin Pettigrew, gjp25@cam.ac.uk

Study website

Contact information

Mr Gavin Pettigrew
Scientific

Department of Surgery
University of Cambridge
Addenbrooke's Hospital
Hills Road
Cambridge
CB2 0QQ
United Kingdom

ORCID ID	0000-0003-3724-9945
Phone	+44 (0)1223 588915
Email	gjp25@cam.ac.uk

Ms Anna Sidders
Public

NHS Blood and Transplant Clinical Trials Unit
Cambridge Blood Centre
Long Road
Cambridge
CB2 0PT
United Kingdom

Phone	+44 (0)1223 588915
Email	sonar@nhsbt.nhs.uk

Study information

Eligibility

Locations

Countries of recruitment

• England
• Scotland
• United Kingdom

Study participating centres

Sponsor information

Cambridge University Hospitals NHS Foundation Trust
Hospital/treatment centre

Addenbrooke's Hospital
Hills Road
Cambridge
CB2 0QQ
England
United Kingdom

Phone	+44 (0)1223 348468
Email	r&denquiries@addenbrookes.nhs.uk
Website	http://www.cuh.org.uk/
"ROR"	https://ror.org/04v54gj93

University of Cambridge
University/education

The Chancellor, Masters, and Scholars of the University of Cambridge
The Old Schools
Trinity Lane
Cambridge
CB2 1TN
England
United Kingdom

Phone	+44 (0)1223 769291
Email	researchgovernance@medschl.cam.ac.uk
Website	http://www.cam.ac.uk/
"ROR"	https://ror.org/013meh722

Funders

Funder type

Government

Results and Publications

Study outputs

Editorial Notes

22/05/2024: Publication reference added.
14/11/2023: The total final enrolment was added.
04/03/2021: Trial’s existence confirmed by the National Institute for Health Research (NIHR).