Condition category
Urological and Genital Diseases
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status

Plain English Summary

Background and study aims
Most people with kidney failure need blood cleaning treatment (haemodialysis) for four hours three times a week up at a hospital/ clinic. This is for the rest of their life unless they are fit to receive a kidney transplant. Survival and quality of life on haemodialysis are poor. The addition of filtration (the removal and replacement of fluid) to regular haemodialysis (which allows toxins to leave the blood with minimal fluid removal/ replacement) is known as haemodiafiltration. The aim of this study is to see whether removing and replacing 21 or more litres of fluid from the blood at the time of a standard dialysis treatment reduces death or hospitalisation from cardiac events or infections in people with kidney failure. Effects on quality of life, admission to hospital, symptoms, infection rates and costs are also examined.

Who can participate?
Adults aged 18 and older who are receiving dialysis treatments three times a week.

What does the study involve?
This study will randomly allocate patients already on dialysis in one of 20 centres in the UK are randomly allocated to switch to either haemodialysis or haemodiafiltration. This does not noticeably change the dialysis procedure as far as the patient is concerned – it is still 4 hours 3 times a week – it just requires changes in equipment and nurse practice. It does however require a greater volume of high quality water. A research nurse collects the initial clinical information. All follow-up is carried out using data already routinely collected by the UK Renal Registry or by linking with other health care databases. Quality of life information are collected. Interviews are carried out and conversations studied in the preparatory and recruitment stages of the study.

What are the possible benefits and risks of participating?
Participants may benefit haemodiafiltration may improve survival as it may remove toxins more effectively, especially if high volumes are used (i.e. more than 21L of water removed and replaced per session. On the downside, such volumes of filtration could remove essential proteins or introduce toxins or infections from the water supply. Therefore it is needed to establish if haemodiafiltration results in benefits to patients, is safe and justifies any additional financial and environmental (e.g. water) costs.

Where is the study run from?
This study is being run by the University of Bristol (UK) and takes place in different hospitals in the UK.

When is the study starting and how long is it expected to run for?
May 2017 to March 2024 (updated 14/01/2020, previously: April 2022)

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

Who is the main contact?
1. Dr Sunita Procter
2. Dr Fergus Caskey

Trial website

Contact information



Primary contact

Dr Sunita Procter


Contact details

Travel to Work Study Manager
School of Social and Community Medicine
University of Bristol
Canynge Hall
39 Whatley Road
United Kingdom
+44 117 928 7284



Additional contact

Dr Fergus Caskey


Contact details

Learning and Research
Southmead Hospital
BS10 5NB
United Kingdom
+44 117 414 8150

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

The High-volume Haemodiafiltration vs High-flux Haemodialysis Registry Trial



Study hypothesis

The aim is to establish the effectiveness and cost-effectiveness of high-volume HDF compared with high-flux HD in adult patients with ESKD on maintenance thrice weekly in-centre HD. This will be done by running a randomised controlled trial using non-cancer mortality or hospital admission due to a cardiovascular event or infection as our primary outcome.

Ethics approval

South Central – Berkshire Research Ethics Committee, 07/09/2017, ref: 17/SC/0391

Study design

Randomised; Interventional; Design type: Treatment, Device, Complex Intervention

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Renal failure


Participants in the intervention arm receive in-centre, high-volume, post-dilution HDF typically for four hours, three times a week. Participants in the control arm receive in-centre high-flux HD typically for four hours, three times a week.

Participants in both arms are followed up for 32 months minimum (50 months maximum) using six monthly paper or electronic questionnaires. Follow up data are also accessed by linking to routine healthcare databases i.e. UK Renal Registry, Hospital Episode Statistics and Office for National Statistics data (and their equivalents in Wales, Scotland and Northern Ireland).

Intervention type



Drug names

Primary outcome measure

1. Non-cancer mortality or hospital admission with a cardiovascular event or infection from randomisation to end of follow-up
2. A composite of first of non-cancer mortality or admission to hospital related to a cardiovascular event or infection is measured using datasets (UKRR, Hospital Statistics & ONS) from randomisation to end of follow-up (32-50 months depending on recruitment)

Secondary outcome measures

1. All-cause mortality, cardiovascular and infection related morbidity and mortality. Health-related quality of life (QoL), cost effectiveness and environmental impact
2. All-cause mortality is measured using datasets (UKRR and ONS) from randomisation to end of follow-up (32-50 months depending on recruitment)
3. Cardiovascular – cause specific hospitalisation and mortality is measured using datasets ((UKRR, Hospital Statistics (HES, PEDW, ISD, NISRA) & ONS) from randomisation to end of follow-up (32-50 months depending on recruitment)
4. Infection – cause- specific hospitalisation and mortality using datasets (MRSA & MSSA) (Public Health England) from randomisation to end of follow-up (32-50 months depending on recruitment)
5. Health-related quality of life (QoL) – quality adjusted life years gained (EQ-5D-5L), generic quality of life (SF-36), disease specific (kidney symptoms within KDQOL-36) and time to recover after dialysis: From Patient Questionnaires - assessed using repeated measures taken six-monthly
6. Cost effectiveness and environmental impact (including locally purified water, manufactured saline and plastic consumables): using all available data for the full duration of follow-up (32-50 months)

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Adult patients aged 18 and older receiving in-centre, maintenance HD or HDF for ESKD
2. Dialysing three times a week in a main dialysis unit or satellite unit
3. Potential to achieve high-volume HDF

Participant type


Age group




Target number of participants

Planned Sample Size: 1550; UK Sample Size: 1550

Participant exclusion criteria

1. Lack of capacity to consent
2. Clinician predicted prognosis of less than 3 months
3. Started maintenance HD within the preceding 4 weeks
4. Transition to living kidney donor transplant or home dialysis scheduled within next 3 months
5. Not suitable for high-volume HDF for other clinical reasons such as dialysis less than thrice weekly or unlikely to achieve sufficient blood flow rates with current vascular access
6. Treatment with HDF for more than 3 months prior to inclusion in the trial or prior intolerance of HDF

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Southmead Hospital
North Bristol NHS Trust (Lead Centre) Southmead Road Westbury-On-Trym
BS10 5NB
United Kingdom

Trial participating centre

Queens Medical Centre
Nottingham University Hospitals NHS Trust Trust Headquarters Derby Road Nottinghamshire
United Kingdom

Trial participating centre

Ipswich Hospital NHS Trust
Heath Road Ipswich Suffolk
United Kingdom

Trial participating centre

Salford Royal Hospital
Salford Royal NHS Foundation Trust Stott Lane Salford Greater Manchester
M6 8HD
United Kingdom

Trial participating centre

Freeman Hospital
The Newcastle-Upon-Tyne Hospitals NHS Foundation Trust Freeman Road High Heaton
United Kingdom

Trial participating centre

Edinburgh Royal Infirmary Renal Department
51 Little France Drive
EH16 4SA
United Kingdom

Trial participating centre

Bradford Royal Infirmary
Bradford Teaching Hospitals NHS Foundation Trust Duckworth Lane
United Kingdom

Trial participating centre

University Hospitals Of North Midlands NHS Trust
Newcastle Road Staffordshire
United Kingdom

Trial participating centre

Aberdeen Royal Infirmary Renal Unit
AB25 2ZN
United Kingdom

Trial participating centre

Queen Elizabeth University Hospital Renal Unit
1345 Govan Road
G51 4TF
United Kingdom

Sponsor information


North Bristol NHS Trust

Sponsor details

Southmead Hospital
Southmead Road
BS10 5NB
United Kingdom

Sponsor type

Hospital/treatment centre



Funder type


Funder name

National Institute for Health Research

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

National government


United Kingdom

Results and Publications

Publication and dissemination plan

Academic publications will be targeted at high impact general medical journals such as the BMJ, the New England Journal of Medicine and the Journal of the American Medical Association. Findings will be presented at leading nephrology conferences in Europe (the ERA-EDTA Annual Congress) and North America (The American Society of Nephrology Kidney Week) as well as at the UK Kidney Week, co-hosted by the Renal Association and the multi-disciplinary British Renal Society. Findings will also be used to inform future iterations of the NICE-approved UK Renal Association clinical guidelines and the European Renal Best Practice clinical guidelines.

The H4RT protocol is available at reference URL:
A statistical analysis plan approved by the trial steering committee will be made publicly available in due course.

IPD sharing statement:
The data sharing plans for the current study are unknown and will be made available at a later date

Intention to publish date


Participant level data

To be made available at a later date

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

14/01/2020: The following changes were made to the trial record: 1. The recruitment end date was changed from 31/12/2019 to 31/03/2021. 2. The overall end date was changed from 30/04/2022 to 31/03/2024. 3. The intention to publish date was changed from 30/04/2023 to 31/03/2025. 4. The plain English summary was updated to reflect these changes. 07/10/2019: The recruitment end date was changed from 30/09/2019 to 31/12/2019. 08/05/2019: The recruitment end date was changed from 30/04/2019 to 30/09/2019. 03/04/2019: The condition has been changed from "Specialty: Renal disorders, Primary sub-specialty: Renal disorders; UKCRC code/ Disease: Renal and Urogenital/ Renal failure" to "Renal failure" following a request from the NIHR. 26/10/2017: Internal review.