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

Plain English Summary

Background and study aims
Kidney stones are stone-like lumps that can develop in one or both of the kidneys. Although some stones do not cause pain or discomfort, patients can develop serious pain, infection, blood in urine, kidney problems or even kidney failure. Many stones occur in the lower part of the kidney (lower pole stones). These stones are more likely to require treatment because they are less likely to pass on their own. Currently within the NHS there are three treatment options for lower kidney stones: extracorporeal shockwave lithotripsy (ESWL), percutaneous nephrolithotomy (PNL), and flexible ureterorenoscopy with laser lithotripsy (FURS). We are uncertain which of these treatments is best at getting rid of stones and which is best value for patients and the NHS. They each have advantages and disadvantages (benefits and harms). The aim of this study is to determine the clinical effectiveness and cost effectiveness of these three treatment options for lower kidney stones.

Who can participate?
Patients aged 16 or over with lower pole kidney stones.

What does the study involve?
Patients with smaller stones are randomly allocated to be treated with either FURS or ESWL. Patients with larger stones are randomly allocated to be treated with either FURS or PCNL. In FURS, a small telescope is passed into the bladder through the urethra and up to the kidney, and a laser beam breaks the stone into pieces, which are then either retrieved or the passed spontaneously after the procedure. In ESWL, shockwaves from a machine outside the body target and break the stone into pieces, which are then passed spontaneously. In PCNL, a hole is made in the skin, a tube is inserted through it into the kidney, and a small telescope is inserted into the kidney via the tube to break the stone and remove all the pieces.

What are the possible benefits and risks of participating?
Patients undergoing FURS require an anaesthetic and sometimes a hospital stay, and there is a small risk of complications (e.g., infection, bleeding). ESWL does not need an anaesthetic nor hospital stay, but passing the pieces can take time, more than one treatment may be needed for larger stones, and some pieces may not pass at all. PCNL usually clears the stone completely in one go, but needs an anaesthetic, hospital stay, and may cause more serious problems (bleeding and infection). We think FURS may clear the stone more efficiently than ESWL, but less well than PNL.

Where is the study run from?
Aberdeen Royal Infirmary (UK).

When is the study starting and how long is it expected to run for?
May 2015 to December 2020.

Who is funding the study?
National Institute for Health Research Technology Assessment Programme (NIHR HTA) (UK).

Who is the main contact?
Prof Samuel McClinton

Trial website

Contact information



Primary contact

Prof Samuel McClinton


Contact details

NHS Grampian
Department of Urology
Aberdeen Royal Infirmary
AB25 2ZB
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number

HTA 13/152/02

Study information

Scientific title

The clinical and cost effectiveness of surgical interventions for stones in the lower pole of the kidney: the percutaneous nephrolithotomy, flexible ureterorenoscopy and extracorporeal lithotripsy for lower pole kidney stones randomised controlled trial (PUrE RCT)



Study hypothesis

The null hypotheses being tested are:
1. The use of flexible urterorenoscopy with laser lithotripsy (FURS) to treat lower pole kidney stones less than 10 mm will not be superior to extracorporeal shockwave lithotripsy (ESWL) as assessed by a relative increase of at least 0.3 of a standard deviation (SD) on the EQ-5D AUC up to 12 weeks post treatment
2. The use of FURS to treat lower pole stones of the kidney 10 mm or greater and less than or equal to 25 mm will not be superior to percutaneous nephrolithotomy (PCNL) by an increase of 0.3SD on the EQ-5D AUC up to 12 weeks post treatment.

Further information can be found at:

Ethics approval

North of Scotland Research Ethics Committee, 10/11/2015, REC ref: 15/NS/0113

Study design

Two separate pragmatic multicentre patient-randomised open-label superiority randomised controlled trials with an initial internal pilot phase

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


Lower pole kidney stones


RCT 1: FURS versus ESWL for stone sizes <=10 mm
RCT 2: FURS versus PCNL for stone sizes >10mm <=25 mm

A flexible ureteroscope is passed into the kidney and a holmium laser fibre used to fragment stones. Stone fragments are then either retrieved or the patient passes them spontaneously after the procedure.

A small incision is made in the skin through which a tube is inserted into the kidney. A nephroscope is inserted via this tube to retrieve the stone, or fragment it before retrieval. The intention is to remove all stone fragments.

An external acoustic pulse (shockwave), from outside the body is focused onto the kidney stone, causing it to fragment. Stone fragments are then passed spontaneously by the patient in the days following the treatment. It may be delivered by fixed (static, on-site) or mobile (external) machines.

Intervention type



Drug names

Primary outcome measure

1. Patient-reported: Health status (EQ-5D-5L) area under the curve (AUC) to 12 weeks post intervention, based upon EQ-5D completion at fixed time points; at baseline (recruitment), just prior to initial intervention (FURS, PCNL or first session of ESWL), at 1, 2, 4, 8, and 12 weeks after initial intervention, and at variable time points; just prior and 1 week after any additional intervention (including planned additional ESWL sessions and removal of stent) and once during hospitalisation for adverse events related to treatment (e.g. pain and infection).
2. Economic: Incremental cost per quality adjusted life year (QALYs) gained at 12 months post-randomisation based on the estimated NHS costs and participant responses to the EQ-5D (including additional time point at 12 months).

Secondary outcome measures

1. Patient reported:
1.1. Severity of pain as measured by the Numeric Rating scale (NRS; completed with EQ-5D-5L)
1.2. Generic health profile as measured by the SF-12 (completed at baseline and 12 months)
1.3. Use of analgesia (completed with NRS and EQ-5D)
2. Clinical:
2.1. Stone clearance measured at between 8 and 12 weeks post initial intervention using renal imaging (CTKUB preferred but plain x-ray and ultrasound acceptable). Measured by local trial staff and categorized as complete, acceptable, or unacceptable. Also maximum dimension of the largest fragment of the treated stone in mm
2.2. Need for additional treatment (carried out or planned) at 12 weeks post-initial treatment and 12 months post randomisation
2.3. Complications during initial intervention. Intervention-related complications at 12 weeks (categorised by Clavien-Dindo classification) post treatment and up to 12 months post randomisation. All measured by site staff and entered on CRF.
3. Economic:
3.1. NHS primary and secondary care resources used and their costs
3.2. Patient costs (out of pocket), time off work up to 12 months post randomisation
Data gathered from completion of CRFs by site staff and participant questionnaire at 12 weeks post initial treatment and 12 months post randomisation.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Adults ≥16 years of age
2. Lower pole stone ≤25 mm in maximum dimension with decision to treat that stone
3. Presence of stone confirmed by CTKUB
4. Able and willing to undergo either treatment for specified stone size
5. Capacity to give informed consent to participate in trial which includes adherence to trial requirements

Participant type


Age group




Target number of participants

1044 (522 in each RCT)

Participant exclusion criteria

1. Pregnancy
2. Patients with co-existing stone that takes precedence in deciding treatment modality (such as obstructing ureteric stone or large upper pole stone)
3. Patients with health or other factors that are absolute contraindications to an intervention that they may be allocated
4. Patients unable to understand or complete trial documentation

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Aberdeen Royal Infirmary
Department of Urology Ward 44 Foresterhill
AB25 2ZB
United Kingdom

Sponsor information


University of Aberdeen (UK)

Sponsor details

Research and Innovation
King's College
Regent Walk
AB24 3FX
United Kingdom
+44 (0)1224 272 123

Sponsor type




Grampian Health Board (UK)

Sponsor details

Research and Development Office
Foresterhill Annexe
AB25 2ZD
United Kingdom
+44 (0)1224 553 846

Sponsor type




Funder type


Funder name

National Institute for Health Research Technology Assessment Programme (NIHR HTA)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

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