The study is designed to test different ways of estimating kidney function. The best way of measuring kidney function is time consuming and expensive, so estimates are normally used instead. eGFR-C will look at which method of estimating is most accurate.
If you are willing to take part, you will be asked to sign a consent form. The research nurse will go through an information form with you to check your details and ask about your medications and other illnesses you have or may have had. You will be asked to give your ethnic origin and your height, weight, waist and hip circumference and blood pressure will be measured. You don't need to fast on the morning of the test. We will take some blood samples (a total of 20 mL, about 4 teaspoons) and a urine sample from you for measurement of kidney function and store some blood and urine for measurement of other kidney markers in a central laboratory.
The research team will then give you a small injection of a substance called iohexol into a vein. Four further blood samples will then be then taken (4 mL, just under a teaspoon, each time) over a period of four hours to measure how efficiently your kidneys have cleared the iohexol injection from your blood. In total the visit takes approximately five hours to complete. This will be the end of your first visit.
You will then be followed up in clinics at 6, 12, 18, 24 and 30 months to assess your kidney function. These visits may be a part of your routine hospital care and should be very short - around 10 minutes. At each of these visits we will ask you to provide a blood sample and a urine sample for tests of kidney function. The final visit will take place after 36 months. At this last visit all of the tests and measures from the first visit, including the iohexol injection procedure, will be repeated. This will be the end of the study and after this your care will continue as normal.
You may be asked if you would also like to participate in a sub-study (an extra study within the main study) looking at patterns of what happens to chronic kidney disease with time. We will ask 375 of the 1300 patients in the study to be included in this sub-study. Your participation in the sub-study is optional and will be exactly the same as that detailed above but will also involve having the iohexol injection procedure and at 12 months and 24 months in addition to the initial and 36 months iohexol injection procedures. At 12 and 24 months your medical history will be taken and height, weight, waist and hip circumference and blood pressure will also be measured again. If you are willing to participate please let the research nurse know at your appointment and you will be asked to indicate your wish to participate on the consent form.
After all 1300 participants have reached the three year test the results will be compared, analysed, and published.