Plain English Summary
Background and study aims
Acute kidney injury (AKI) occurs when the kidneys suddenly stop working properly. It can cause complete kidney failure which is a very serious condition that can lead to death. It usually occurs after complications from illness or surgeries. AKI occurs in an estimated 36% of patients after a cardiac (heart) surgery. Therefore, people undergoing cardiac surgery are at a higher risk of AKI. However, it is hard to accurately predict the risk of AKI. There are tests that can evaluate renal function (how well the kidney works) by measuring creatinine levels in the kidneys (a type of waste that needs to be filtered by the kidneys to be then eliminated by urine (peeing)). This type of test could be used to see if there are indicators for risk of future AKI. The aim of this study is to examine kidney function prior to surgery is able to predict risk for AKI after surgery.
Who can participate?
Adults over the age of 18 who are undergoing elective cardiac surgery.
What does the study involve?
Participants undergo a kidney stress test prior to their elective cardiac surgery. This test takes seven hours and includes five measurements of serum creatinine (blood samples) and five one-hour urine samples in order to estimate creatinine levels. Participants then have their surgery and are followed up for seven days through daily blood tests to assess creatinine blood levels and by monitoring their urine levels. Three months after surgery, participants undergo another kidney stress test to evaluate renal function.
What are the possible benefits and risks of participating?
There are no notable benefits or risks with participating.
Where is the study run from?
San Bortolo Hospital (Italy)
When is the study starting and how long is it expected to run for?
April 2014 to February 2016
Who is funding the study?
San Bortolo Hospital (Italy)
Who is the main contact?
Dr Faeq Husain-Syed
Use of preoperative renal function reserve to predict risk of acute kidney injury after cardiac surgery
The aim of this study is to see whether preoperative renal functional reserve predicts risk for acute kidney injury after cardiac surgery.
Ethical Committee of the Province Vicenza Italy, 20/08/2014, ref: n63/14
Observational cohort study
Primary study design
Secondary study design
Patient information sheet
See additional files (in Italian)
Acute kidney injury after cardiac surgery
Participants with normal glomerular filtration rates who are undergoing an elective cardiac surgery are included in this study. Participants undergo a preoperative kidney stress test using high oral protein loads. This is then repeated three months after surgery. The kidney stress test takes seven hours and includes five measurements of serum creatinine and five one-hour urine collection in order to estimate creatinine clearance.
Participants are followed for occurrence of postoperative acute kidney injury (AKI) for seven days after the surgery through daily serum creatinine blood tests and hourly urine output measurements according to the Acute Kidney Injury Guidelines of Kidney Disease Improving Global Outcomes (KDIGO).
Urine samples are taken from participants prior to surgery, thirty minutes after the cardiac bypass, at admission to the intensive care unit, at four, 12 and 24 hours after surgery and when participants are discharged from the hospital in order to examine urinary biomarkers.
Renal function is measured three months after surgery by repeating the kidney stress test.
Primary outcome measures
1. Renal functional reserve (RFR) is measured using a high oral protein load kidney stress test at baeline (before cardiac surgery) and three months after surgery
2. Acute kidney injury is measured using KDIGO criteria seven days after surgery
Secondary outcome measures
1. Occurrence of acute kidney injury impact the RFR is measured using Kidney Disease Improving Global Outcomes criteria at three months after surgery
2. Urinary biomarkers (TIMP-2 and IGFBP7) to predict loss of RFR are measured using urine samples at basline, 30 minutes after initiation of cardiopulmonary bypass, at intensive care unit admission, four, 12 and 24 hours after surgery and at hospital discharge
Overall trial start date
Overall trial end date
Participant inclusion criteria
1. Older than 18 years
2. Undergoing elective cardiac surgery
3. Signed informed consent forms
Target number of participants
Participant exclusion criteria
2. Chronic kidney disease ≥ stage III
3. Solitary kidney
4. Diabetes mellitus type 1
5. Recent cardiac arrest
6. Liver failure or cirrhosis
7. Total parenteral nutrition
8. Hemoglobin <11 g/dl
10. History of malabsorption, chronic inflammatory bowel disease, short bowel, or pancreatic insufficiency
11. Transplant donor or recipient
12. Active autoimmune disease with renal involvement
14. Prostate hypertrophy with International Prostate Symptom Score ≥20
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
San Bortolo Hospital, Department of Cardiac Surgery
Via Rodolfi 37
San Bortolo Hospital Italy
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
It is planned for publication in a high-impact peer reviewed journal.
IPD sharing plan:
The datasets generated during and/or analysed during the current study are/will be available upon request from Dr Faeq Husain-Syed at firstname.lastname@example.org
Intention to publish date
Participant level data
Available on request
Results - basic reporting