Formulae of estimated glomerular filtration rate (eGFR) based on serum creatinine (Scr) are routinely\nused in oncology patients, however, they are inaccurate in some populations. Our aim was to assess the agreement\nof eGFR formulae and thereby build a nomogram to predict the reliability of estimates.\nMethods: Measured GFR (mGFR) using isotope from 445 oncology patients were compared with eGFR from six\nformulae (Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD), modified MDRD formulae for Chinese (CMDRD),\nChronic Kidney Disease Epidemiology (CKD-EPI) Collaboration, Wright and full age spectrum (FAS)). Bias,\nprecision and accuracy of eGFR formulae were examined. We also evaluated statistics of agreement: the total\ndeviation index (TDI), the concordance correlation coefficient (CCC) and the coverage probability (CP). Multivariate\nlogistic regression was applied to identify characteristics associated with inaccurate eGFR and construct a predictive\nnomogram.\nResults: All eGFR formulae tended to overestimate the eGFR. The percentage of patients with eGFR within 30% the\nmGFR ranged from 38.0 to 62.8%. Cockcroft-Gault and MDRD showed low bias and high precision. The MDRD\nformula exhibited lowest TDI, meaning that 90% of estimations ranged from -36 to 36% of mGFR. Multivariate\nlogistic regression showed that inaccuracy of MDRD was found in elderly patients or in patients with eGFR greater\nthan 120 ml/min. A nomogram was constructed to help oncologists to predict the risk of inaccuracy of eGFR. The\ncalibration curve showed good agreement.\nConclusions: Our results suggest that the error of eGFR by any formulae was common and wide in Chinese\noncology patients. Our nomogram may assist oncologists in decision-making when mGFR is needed.
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