Individualized calibration of estimated glomerular filtration rate for serial renal function determination: a pilot study

Kidney function evaluation is crucial to the practice of medicine. Glomerular filtration rate (GFR) is commonly accepted as the best measure of renal function. In most clinical settings, GFR is usually estimated. However, in some clinical scenarios, measuring GFR is mandatory. The currently used methods to measure GFR are comparatively expensive and time-consuming. As a compromise between measured and estimated GFR, an individually calibrated estimated GFR (iceGFR) equation was developed, and its performance was compared to conventional estimated GFR (eGFR) and a population calibrated estimated GFR (pceGFR). Data from fifty-three (53) patients who had serial ^99mTc-DTPA GFR measurements and had a serum creatinine measurement within 3 months of each GFR measurement were included. Bland-Altman analyses were used to compare eGFR, pceGFR and iceGFR to a reference mGFR with respect to bias and limits of agreement. Fifty-three patients were included in the final analysis. Compared to mGFR, the biases of eGFR, pceGFR and iceGFR were - 16, - 5 and - 3 ml/min/1.73 m² respectively, with the biases of pceGFR and iceGFR significantly lower than eGFR. The precision of iceGFR was significantly better than both eGFR and pceGFR. In this proof of concept pilot study iceGFR performed better than both eGFR and pceGFR.