Estimation of glomerular filtration rate in cancer patients.
The frequent need to obtain an estimate of renal function in cancer patients, not least for targeting carboplatin dose, has led to a number of approaches to estimate glomerular filtration rate (GFR). This study aimed to develop a simple and reliable method to estimate GFR using readily-available patient characteristics. Data from 62 patients with estimates of 51Cr-EDTA clearance were analysed to determine the most appropriate formula relating this method of measuring GFR to patient characteristics. The population pharmacokinetics of 51Cr-EDTA were analysed using NONMEM to evaluate the influence of each covariate. The formulae derived were then validated using a further 38 patients and compared with those obtained using existing formulae. 51Cr-EDTA clearance (GFR) was positively related to Dubois surface area, negatively related to age, and inversely related to serum creatinine (SCr). Females had lower 51Cr-EDTA clearance than males. The enzymatic method of SCr assay gave more reliable results than the Jaffe colorimetric method. A measure of creatine kinase significantly improved the estimation of GFR. The new formula produced estimates of GFR which were less biased (Mean Prediction Error = -3%) and more precise (Mean Absolute Prediction Error = 12%) than Cockcroft and Gault (-8% and 16%) or Jelliffe (-15% and 19%) estimates. The formulae developed here can be used to provide reliable estimates of GFR, particularly in regard to targeted dosing of carboplatin.
Wright
J G
JG
Department of Oncology, University of Newcastle, UK.
Boddy
A V
AV
Highley
M
M
Fenwick
J
J
McGill
A
A
Calvert
A H
AH
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000493:pharmacokinetics; D016190:Carboplatin / Q000493:pharmacokinetics; D002614:Chelating Agents; D002860:Chromium Radioisotopes; D004492:Edetic Acid; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009369:Neoplasms / Q000150:complications* / Q000188:drug therapy
D000970:Antineoplastic Agents; D002614:Chelating Agents; D002860:Chromium Radioisotopes; D004492:Edetic Acid; D016190:Carboplatin