Comparison of Performance of Improved Serum Estimators of Glomerular Filtration Rate (GFR) to ^99mTc-DTPA GFR Methods in Patients with Hepatic Cirrhosis

Abstract

Glomerular filtration rate (GFR) measurements are critical in patients with hepatic cirrhosis but potentially erroneous when based on serum creatinine. New equations for estimated GFR (eGFR) have shown variable performance in cirrhotics, possibly because of inaccuracies in reference methods for measured GFR (mGFR). The primary objective was to compare the performance of 4 improved eGFR equations with a 1-compartment, 2-sample plasma slope intercept 99m Tc-DTPA mGFR method to determine whether any of the eGFR calculations could replace plasma 99m Tc-DTPA mGFR in patients with cirrhosis. The secondary objective was to test the hypothesis that mGFR using voluntary voided urine collections introduces error compared with plasmaonly methods. Methods: Fifty-four patients with hepatic cirrhosis underwent mGFR determinations from 2 plasma samples at 1 and 3 h after intravenous administration of 185 MBq of 99m Tc-DTPA. GFR was also generated by a UV/P calculation derived from blood and urine samples. These mGFRs were compared with the eGFRs generated by 4 estimating equations: MDRD (Modified Diet in Renal Disease), CKD-EPI (Chronic Kidney Disease-Epidemiology Collaboration) (serum creatinine [SCr]), CKD-EPI (cystatin [CysC]), and CKD-EPI (CysC1SCr). eGFRs were compared with mGFRs by Pearson correlation, precision, bias, percentage bias, and accuracy (eGFRs varying by ,10% [p10], ,20% [p20] or ,30% [p30] from the corresponding mGFR). Results: All eGFRs showed poorer performance when the UV/P 99m Tc-DTPA mGFR was used as the reference than when the plasma 99m Tc-DTPA mGFR was used. When compared with the plasma 99m Tc-DTPA mGFR method, the performance of all eGFR equations was superior to most published reports. There was a moderately good positive correlation between eGFRs and mGFRs. When compared with plasma 99m Tc-DTPA mGFR, precision of eGFRs was in the range of 14-20 mL/min and showed a negligible bias. Compared with the plasma 99m Tc-DTPA mGFR, CKD-EPI (CysC1SCr) showed the best overall performance and accuracy, at 85.19% (p30), 75.93% (p20), and 42.59% (p10). Conclusion: Estimating equations for measuring eGFR performed better than in most published reports, attributable to use of the plasma 99m Tc-DTPA mGFR method as a reference. CKD-EPI (CysC1SCr) eGFR showed the best overall performance. However, more discriminating methods may be required when accurate GFR measurements are necessary. mGFR measurements using urine collections may introduce error compared with plasma-only methods.

Evaluation of the Royal Free Hospital Cirrhosis Glomerular Filtration Rate Formula in Hispanic Patients with Cirrhosis: An External Validation

“…It is important to emphasize that the precision and accuracy reported by Kalafateli et al 8 with the CKD-EPI CystC formula (assessed only in the external validation cohort of 82 patients) was a p30 of 26.8% (95% CI: 17.8-37.1). Such figure contrasts considerably with the results from our cohort and with the majority of studies published at present [3][4][5]17,21 , in which in the cystatin C-based formulas, cystatin C is considered the biomarker with greater precision and accuracy for estimating glomerular filtration in patients with LC. Both formulas (RFH and CKD-EPI CystC) performed very similarly with respect to precision and accuracy, as well as to the underestimation of kidney function in patients with filtration > 60 ml/min/1.73m 2 and overestimation in those with filtration <60 ml/min/1.73m 2 (Fig.…”

“…In the MELD score, which is the international classification for organ allocation for liver transplantation, SCr has been included as an essential marker for the evaluation of transplantation, and it is the section of the score that has the most impact on mortality 1 5. Today, GFR calculated through equations based on creatinine has been shown to be inaccurate and imprecise in patients with cirrhosis, when compared with measured GFR, because the formulas are standardized in the general population 4,16,17 . In addition to presenting with factors that modify SCr concentrations, such as age, female sex, muscle mass, and nutritional status, among others, patients with LC present with high bilirubin levels that directly interfere with the diagnostic assay 15 .…”

Correlations between estimating GFR methods and oncological outcomes during cancer chemotherapy

“…All patients had pre-treatment and post-treatment serum creatinine, cystatin c, eGFR levels according to Cockcrauft-Gault, MDRD and CKD-EPI were calculated as referenced before [4,5]. Blood samples were taken at least 8 hours after fasting.…”

“…Exact calculation and determining of the glomerular filtration rate (GFR) is one of the most important criteria to calculate the dosages of chemotherapeutics in cancer patients, according to chemotherapeutics narrow blood level range. Unfortunately, we do not have satisfactory calculation methods excluding the invasive GFR calculating methods in oncology practice [4]. Direct measurement of GFR methods are the gold standards such as clearance of chromium-51 EDTA (51Cr-EDTA), inulin clearance, but these methods needs administration time, necessitate high expertise and have higher cost to use each patients in daily routine [5].…”

Estimation of glomerular filtration rate in patients with cirrhosis: evaluation of equations currently used in clinical practice and validation of Royal Free Hospital cirrhosis glomerular filtration rate

“…Cystatin-C, a protein almost entirely filtered by the kidneys, has been proposed as a more suitable marker of GFR in patients with cirrhosis. Many studies have reported better estimation of GFR with Cystatin-C-based equations [9][10][11][12][13][14][15]. However, Cystatin-C is not available in most institutions, and even in those used, its measurement is significantly more expensive than the…”