Accuracy of glomerular filtration rate (GFR) estimation using creatinine and cystatin C and albuminuria for monitoring disease progression in patients with stage 3 chronic kidney disease: the eGFR-C study

ISRCTN ISRCTN42955626
DOI https://doi.org/10.1186/ISRCTN42955626
ClinicalTrials.gov number NCT02433002
Secondary identifying numbers HTA 11/103/01, UKCRN ID 15268
Submission date
26/09/2013
Registration date
08/10/2013
Last edited
29/07/2024
Recruitment status
No longer recruiting
Overall study status
Completed
Condition category
Urological and Genital Diseases
Prospectively registered
Protocol
Statistical analysis plan
Results
Individual participant data

Plain English Summary

http://www.birmingham.ac.uk/research/activity/mds/trials/bctu/trials/renal/egfr-c/participants/index.aspx

Study website

Contact information

Mr Ryan Ottridge
Scientific

Birmingham Clinical Trials Unit
Public Health Building
University of Birmingham
Birmingham
B15 2TT
United Kingdom

Study information

Study designObservational prospective longitudinal cohort study
Primary study designObservational
Secondary study designCohort study
Study setting(s)Hospital
Study typeScreening
Participant information sheet Patient information can be found at http://www.birmingham.ac.uk/research/activity/mds/trials/bctu/trials/renal/egfr-c/participants/sheet.aspx
Scientific titleAccuracy of glomerular filtration rate (GFR) estimation using creatinine and cystatin C and albuminuria for monitoring disease progression in patients with stage 3 chronic kidney disease - prospective longitudinal study in a multi-ethnic population: the eGFR-C study
Study acronymeGFR-C
Study hypothesisThe eGFR-C study will assess the accuracy of current and alternative tests of kidney function against a reference test in people with moderate (stage 3) chronic kidney disease (CKD).

More details can be found at: http://public.ukcrn.org.uk/Search/StudyDetail.aspx?StudyID=15268
More details can be found at: http://www.nets.nihr.ac.uk/projects/hta/1110301
Protocol can be found at: https://www.birmingham.ac.uk/egfrc/documents (version 4.0 02.02.17)
Ethics approval(s)South East Coast – Surrey REC, 09/10/2013, ref 13/LO/1349
ConditionTopic: Renal and Urogenital; Subtopic: Renal and Urogenital (all Subtopics); Disease: Renal
InterventionMain study: 1300 patients. Biological variability study: In a sub-study 20 participants will undergo the reference test four times over four weeks and then exit the study.

Iohexol GFR tests, 1300 participants will undergo baseline (month 0) and final (month 36) reference GFR, estimated GFR (eGFR) and urinary albumin-to-creatinine ratio (ACR) tests. Additionally they will provide ACR and eGFR tests at 6-monthly intervals. A subset of the cohort (n=375) will receive annual reference GFR tests.

Participants will be recruited from hospital clinics and GP practices at six major UK centres.

Participants will undergo reference GFR testing at study entry with a second follow-up reference test three years later. The reference test involves injecting a small amount of iohexol into a vein and taking blood samples over the next 4 hours to see how quickly the iohexol disappears from the blood stream as a result of glomerular filtration. The rate at which iohexol disappears is equivalent to the level of kidney function. Blood tests for monitoring kidney function, including testing for creatinine and cystatin C, and measurement of urinary albumin will be done every six months during the study period. Iohexol measured GFR will be accepted as the reference (‘gold standard’) measure of kidney function against which each GFR-estimating equations will be compared. The alternative estimated measures of GFR, derived from measuring substances (creatinine and cystatin C) in the blood, will be compared against the reference test. An important outcome is how much the reference test changes over the three years of the study, and how well the surrogate measures reflect this change. We will also collect accurate test cost data for subsequent cost-effectiveness analysis (e.g. do the relative costs of the tests justify any change in practice due to improved performance of one test compared to another?).

Follow-up length: 36 months
Intervention typeOther
Primary outcome measure1. To estimate and compare the accuracy and precision of GFR-estimating equations based on the Modification of Diet in Renal Disease (MDRD) equation and three Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations using either creatinine or cystatin C or a combination of both in people with stage 3 CKD.
2. To estimate the accuracy and precision of the GFR-estimating equations according to ethnic group (particularly Caucasians, African-Caribbean and South-Asian), and baseline diabetes and proteinuria.
Percentage error in eGFR compared to reference GFR. Values will be computed (primary outcome measures 1 and 2) using baseline data for each of the four eGFR equations, and the proportions within 30% (P30) of the reference standard quoted and compared as a measure of accuracy and precision.
3. To evaluate and compare how accurately these GFR-estimating equations reflect change in GFR over three years. Difference in rate of change in eGFR compared to rate of change in reference GFR. Rates of change will be estimated using linear regression and the change per annum and percentage change per annum compared to baseline values will be computed. Large error will be defined as differing by more than 3 mL/min/1.73 m^2/year or by 5 percent points per annum.
Secondary outcome measures1. To establish which GFR-estimating equation, together with ACR, or ACR alone, most accurately predicts those people that have progressive loss of kidney function (CKD progression). Progressive loss of kidney function defined as decline in GFR of more than 10 mL/min/1.73 m^2/3 years or increase in albuminuria category as defined by Kidney Disease: Improving Global Outcomes (KDIGO).
2. To compare the effectiveness and costs of monitoring strategies for identifying people that have progressive loss of kidney function (CKD progression) utilising different GFR-estimating equations and test schedules, accounting for differences in risk of progression. Measured using Cost per quality-adjusted life-year (QALY).

Sub-study of patterns of disease progression
To estimate and model disease progression (decline in GFR or increase in ACR) according to ethnic group (particularly Caucasians, African-Caribbean and South-Asian), and baseline diabetes and proteinuria. Difference in rate of change in eGFR compared to rate of change in reference GFR based on measurements made every 12 months.

Additional study of intra-individual biological variation
Within-individual (CVI) variation and the critical difference (reference change value, RCV) for reference GFR and the estimated GFR equations.
Overall study start date01/02/2014
Overall study end date30/06/2020

Eligibility

Participant type(s)Patient
Age groupAdult
Lower age limit18 Years
SexBoth
Target number of participantsPlanned Sample Size: 1320; UK Sample Size: 1320
Participant inclusion criteria1. Male and female, aged 18 years or over
2. Patients with stage 3 CKD (GFR 30-59 mL/min/1.73 m2) as defined internationally, diagnosed using Modification of Diet in Renal Disease/Chronic Kidney Disease Epidemiology Collaboration (MDRD/CKD EPI) eGFR (at least two consecutive test results in this range at least 90 days apart, with the most recent test in the last 12 months)
3. Written informed consent
Participant exclusion criteria1. History of untoward reactions to iodinated contrast media or allergy to topical iodine
2. Episode of acute kidney injury in previous 6 months (as defined by the Acute Kidney Injury Network criteria)
3. Amputation of whole or part limb
4. Pregnant or breastfeeding
5. Known alcohol or drug abuse
6. Any clinical condition with an expected survival of less than study duration
7. Inability to comply with study schedule and follow-up
8. Inability to provide informed consent e.g. due to cognitive impairment
Recruitment start date01/02/2014
Recruitment end date31/07/2015

Locations

Countries of recruitment

  • England
  • United Kingdom

Study participating centre

Birmingham Clinical Trials Unit
Public Health Building
University of Birmingham
Birmingham
B15 2TT
United Kingdom

Sponsor information

University of Birmingham (UK)
University/education

Edgbaston
Birmingham
B15 2TT
England
United Kingdom

Website http://www.birmingham.ac.uk
ROR logo "ROR" https://ror.org/03angcq70

Funders

Funder type

Government

NIHR Health Technology Assessment Programme - HTA (UK)

No information available

Results and Publications

Intention to publish date30/06/2021
Individual participant data (IPD) Intention to shareNo
IPD sharing plan summaryNot provided at time of registration
Publication and dissemination planThere will be three different sets of results:
1. A substudy (BVS – biological variability), which has been submitted for publication in 2019.
2. The first primary outcome, accuracy of eGFRs, will be submitted for publication in 2020.
3. The second primary outcome, comparison of eGFRs for monitoring disease progression (over the 3 years of study follow up) will be submitted for publication in 2021.
IPD sharing plan

Study outputs

Output type Details Date created Date added Peer reviewed? Patient-facing?
Protocol article 14/01/2014 Yes No
Results article 01/08/2019 10/08/2020 Yes No
HRA research summary 28/06/2023 No No
Results article 01/07/2024 29/07/2024 Yes No

Editorial Notes

29/07/2024: Publication reference added.
10/08/2020: Publication reference added.
14/02/2020: ClinicalTrials.gov number added.
21/02/2019: The following changes were made to the trial record:
1. The overall trial end date was changed from 31/07/2015 to 30/06/2020.
2. The intention to publish date was changed from 31/12/2018 to 30/06/2021.
3. Contact details, protocol link, and publication and dissemination plan updated.
22/10/2018: The following changes were made:
1. The publication and dissemination plan was added.
2. The intention to publish date was added.
18/10/2018: No publications found, verifying study status with principal investigator