The estimation of glomerular filtration rate in an Australian and New Zealand cohort

Background: Accurate estimation of glomerular filtration rate (GFR) allows early detection of renal disease and maximizes opportunity for intervention. Aim: To assess the accuracy of estimated GFR (eGFR) in an Australian and New Zealand cohort with chronic kidney disease using the 4‐variable Modification of Diet in Renal Disease equation (MDRD_4V), the Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) equations, and the Cockcroft and Gault equation with actual and ideal body weight. Methods: Retrospective review of patients who had measured GFR (mGFR) by 51Cr‐EDTA clearance and simultaneous measurements of serum biochemistry and anthropometrics. eGFR was compared with mGFR using the concordance correlation coefficient (CCC) and Bland–Altman measures of agreement. Results: 178 patients had 441 radioisotope measurements of GFR. Mean mGFR of was 22.6 mL/min per 1.73 m². The MDRD_4V equation using the ‘black’ correction factor was most accurate with a mean eGFR of 19.74 (CCC 0.733, bias ?2.86). The CKD‐EPI equations also using the ‘black’ correction factors were almost as good at 19.11 (CCC 0.719, bias ?3.49). The Cockcroft–Gault creatinine clearance values had the poorest agreement with mGFR. In the 18 nonwhite non‐Asian patients, the MDRD_4V and CKD‐EPI equations were generally less accurate although the use of the ‘black’ correction factor resulted in greater accuracy for both equations. Conclusion: The MDRD_4V equation was the most accurate. However, its accuracy might be less for nonwhite non‐Asian patients if the ‘black’ correction factor is omitted. Further study of the estimation of GFR in Australian and New Zealand ethnic subgroups would be helpful.     

Development and validation of a more accurate estimating equation for glomerular filtration rate in a Chinese population

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Comparison of serum cystatin C and creatinine levels in determining glomerular filtration rate in children with stage I to III chronic renal disease

Abstract

Background: Pediatric studies are relatively scarce on the superiority of cystatin C over creatinine in estimation of glomerular filtration rate (GFR). This study measured cystatin C and serum creatinine levels, and compared GFR estimated from these two parameters in patients with chronic renal disease. Methods: This prospective, observational, controlled study included 166 patients aged 1–18 years diagnosed with stage I to III chronic renal disease, and 29 age- and sex-matched control subjects. In all patients, GFR was estimated via creatinine clearance, Schwartz formula, Zappitelli 1 and Zappitelli 2 formula and the results were compared using Bland–Altman analysis. Results: Patients and controls did not differ with regard to height, body weight, BMI, serum creatinine and serum cystatin levels, and Schwartz formula-based GFR (p?>?0.05). There was a significant relationship between creatinine and cystatin C levels. However, although creatinine levels showed a significant association with age, height, and BMI, cystatin C levels showed no such association. ROC analysis showed that cystatin C performed better than creatinine in detecting low GFR. Conclusion: Cystatin C is a more sensitive and feasible indicator than creatinine for the diagnosis of stage I to III chronic renal disease.     

Simple estimation of the glomerular filtration rate in sick Thai children

The objective of this study was to establish an appropriate formula for the estimation of creatinine clearance (CCr) in sick Thai children, and to evaluate the accuracy of using the Schwartz formula. Children aged between 0 and 19 years with various diseases and varying levels of renal function (but remained stable) were studied. Height in centimetres (L) and weight in kilograms (W), time of urine collection and urine volume were measured to provide urine flow (mL/min (V)) measurements. Body surface area (m2; SA) was also assessed. Quantitative urinary and plasma creatinine concentration (UCr and PCr, respectively) were determined. Creatinine clearance was calculated by using the following formula: UCr x V x 1.73/(PCr x SA). The linear association between CCr and L/PCr derived from these data was compared with the Schwartz formula by using bootstrap statistics. One-hundred and sixty children were studied. A least squares straight-line regression through the origin of CCr against L/PCr provided a good fit to the data. Our dataset revealed no evidence of an age or sex affect on the relationship. Creatinine clearance was estimated by using the following formula: 0.465 x (L/PCr), in which the calculated 95% confidence interval of the coefficient was 0.44-0.49. A comparison of this coefficient with that for the Schwartz formula for children aged > or =1 year (0.55), using 1000 bootstrapped resamples, showed an incompatibility between the two coefficients (P < 0.00005). In conclusion, we suggest estimating CCr in sick Thai children of either sex by using a modification of the Schwartz formula in which the coefficient equals 0.465.     

The association of post-traumatic stress disorder with glomerular filtration rate decline

While major depression is known to be associated with glomerular filtration rate (GFR) decline, there is a lack of data on the association of other mental illnesses like posttraumatic stress disorder (PTSD) with kidney disease. In 640 adult participants of the Heart and Soul Study (mean baseline age of 66.2 years) with a high prevalence cardiovascular disease, hypertension and diabetes, we examined the association of PTSD with GFR decline over a 5-year follow-up. We observed a significantly greater estimated (e) GFR decline over time in those with PTSD compared to those without (2.97 vs. 2.11 ml/min/1.73 m²/year; p = .022). PTSD was associated with 91% (95% CI 12%–225%) higher odds of ‘rapid’ versus ‘mild’ (>3.0 vs. <3.0 ml/min/1.73 m²/per year) eGFR decline. These associations remained consistent despite controlling for demographics, medical comorbidities, other mental disorders and psychiatric medications. In conclusion, our study provides evidence that PTSD is independently associated with GFR decline in middle-aged adults with a high comorbidity burden. This association needs to be examined in larger cohorts with longer follow-ups.     

Estimation of glomerular filtration rate by the MDRD study equation modified for Japanese patients with chronic kidney disease

Background

Accurate estimation of the glomerular filtration rate (GFR) is crucial for the detection of chronic kidney disease (CKD). In clinical practice, GFR is estimated from serum creatinine using the Modification of Diet in Renal Disease (MDRD) study equation or the Cockcroft-Gault (CG) equation instead of the time-consuming method of measured clearance for exogenous markers such as inulin. In the present study, the equations originally developed for a Caucasian population were tested in Japanese CKD patients, and modified with the Japanese coefficient determined by the data.

Methods

The abbreviated MDRD study and CG equations were tested in 248 Japanese CKD patients and compared with measured inulin clearance (Cin) and estimated GFR (eGFR). The Japanese coefficient was determined by minimizing the sum of squared errors between eGFR and Cin. Serum creatinine values of the enzyme method in the present study were calibrated to values of the noncompensated Jaffé method by adding 0.207?mg/dl, because the original MDRD study equation was determined by the data for serum creatinine values measured by the noncompensated Jaffé method. The abbreviated MDRD study equation modified with the Japanese coefficient was validated in another set of 269 CKD patients.

Results

There was a significant discrepancy between measured Cin and eGFR by the 1.0 × MDRD or CG equations. The MDRD study equation modified with the Japanese coefficient (0.881 × MDRD) determined for Japanese CKD patients yielded lower mean difference and higher accuracy for GFR estimation. In particular, in Cin 30–59?ml/min per 1.73?m², the mean difference was significantly smaller with the 0.881 × MDRD equation than that with the 1.0 × MDRD study equation (1.9 vs 7.9?ml/min per 1.73?m²; P P 2, the accuracy was significantly higher, with 85% vs 69% of the points deviating within 50% (P P 2.

Conclusions

Although the Japanese coefficient improves the accuracy of GFR estimation of the original MDRD study equation, a new equation is needed for more accurate estimation of GFR in Japanese patients with CKD stages 3 and 4.     

Tumour diameter and decreased preoperative estimated glomerular filtration rate are independently correlated in patients with renal cell carcinoma

Study Type – Diagnosis (exploratory cohort) Level of Evidence 2b What’s known on the subject? and What does the study add? For over 30 years it has been recognized that there is an association between end‐stage renal disease (ESRD) and the development of malignancy, particularly renal cortical tumour. Observational studies have consistently shown that patients with severely decreased glomerular filtration rate (GFR) develop cancer more frequently than their age‐ and exposure‐matched controls. This study is the first of its kind to look directly at the relationship between GFR and tumour size, in an effort to begin to examine the relationship between kidney function and oncogenesis.

OBJECTIVE

? To examine the relationship between tumour diameter and estimated GFR (eGFR) in patients with renal cell carcinoma (RCC).

PATIENTS AND METHODS

? In total, 1009 patients undergoing partial or radical nephrectomy for unilateral RCC were identified in the Columbia Urologic Database. ? eGFR was calculated using the modification of diet in renal disease equation using demographic data and preoperative serum creatinine values. ? Data on patient demographics, tumour characteristics, and comorbidities were analyzed using univariate and multivariate regression analysis.

RESULTS

? Mean (sd , range) tumour diameter was 5.29 (3.8, 0.3–29) cm. Mean (sd , range) eGFR was 75 (23.4, 3–173) mL/min per 1.73 m². ? In multivariate regression analysis, tumour diameter independently predicted decreased preoperative eGFR (coefficient, ?0.513; P= 0.008) when controlling for hypertension and race. ? Consistent with this, decreased preoperative eGFR independently predicted increased tumour diameter (coefficient, ?0.013; P= 0.007) when controlling for race, histology and smoking status.

CONCLUSION

? Tumour diameter and decreased preoperative eGFR are independently correlated in patients with RCC.     

Effect of alcohol consumption on estimated glomerular filtration rate and creatinine clearance rate.

BACKGROUND: Moderate alcohol consumption is widely recognized as beneficial in the prevention of cardiovascular disease, yet the renal effects of alcohol intake are still controversial. The present study is designed to investigate the influence of alcohol consumption on calculated creatinine clearance rate (CCr) and glomerular filtration rate (GFR) in a Southern Taiwan Pai-Wan aboriginal community with a high prevalence of alcohol consumption. METHODS: This is a cross-sectional community-based study. The 1466 aboriginal subjects, 40-95 years of age, are a stratified random subpopulation identified during an integrative health care programme. They were sampled for drinking patterns. The main outcome measurements were serum creatinine, estimated CCr and GFR. RESULTS: Subjects with alcohol consumption had significantly higher levels of serum triglycerides, high-density lipoprotein cholesterol, uric acid, estimated CCr and GFR values than non-drinkers. Their blood pressure was also significantly higher. They had lower total cholesterol and low-density lipoprotein cholesterol concentrations. Increasing alcohol consumption was independently and significantly associated with a higher level of estimated CCr and GFR when analysed as both a categorical and continuous variable. CONCLUSIONS: The present study shows that chronic alcohol consumption has a negative effect on blood pressure and lipid profile and stimulates the estimated GFR.     

Limitations of glomerular filtration rate equations in the renal transplant patient

This study aims to compare the performance of endogenous creatinine clearance (CL(cr)) and a number of published mathematical equations to calculate glomerular filtration rate (GFR) in renal transplant patients considering (99m)Tc DTPA isotope scan as the reference method. A total of 152 GFR were performed on 81 renal transplant patients. Accuracy of each method was measured at different percentiles. The bias and precision of all the methods were then compared. A paired t-test was used to compare the performance of each calculation to the respective GFR measured by isotope study performed on the same day. In the total population, all calculated methods correlated significantly with the isotope results. Accuracies within specific ranges of the isotope GFR were limited in all equations (agreement with isotope result /= 50 mL/min and Gates in patients with GFR < 50 mL/min. Salazar (D.E. Salazar and G.B. Corcoran, Am J Med 1988; vol. 84: p. 1053) had the least bias in patients with BMI above 30 kg/m(2) and the Davis equation (G.A. Davis and M.H. Chandler, Am J Health Syst Pharm 1996; vol. 53: p. 1028) in patients with BMI <25 kg/m(2). In all analyses, Nankivell (B.J. Nankivell, S.M. Gruenwald, R.D.M. Allen and J.R. Chapman, Transplantation 1995; vol. 59: p. 1683) overestimated GFR by more than 80% and MDRD 1 and 2 in <10% of the time. The results demonstrate the inherited limitation in the currently available equations to calculate GFR in renal transplant patients.     

Inaccuracy of estimated creatinine clearance for prediction of iothalamate glomerular filtration rate

The clinical practice of estimating creatinine clearance (Ccr) from a patient's serum creatinine value by use of various nomograms and prediction formulas is widespread. The predictive accuracy of such Ccr estimates as substitutes for measured values of glomerular filtration rate (GFR) has not been determined. In addition, the effect of patient physical parameters on GFR prediction accuracy has not been assessed. To investigate these issues, 500 predicted Ccr values from each of four versions of the formula of Cockcroft and Gault were statistically compared with GFR values measured by sodium iothalamate clearance (Cio) in 394 human subjects representing every level of renal function. We conclude that (1) the original formula of Cockcroft and Gault is an inaccurate predictor of GFR; (2) correction of the formula for patient physical parameters does improve its accuracy for GFR prediction; (3) the best formula is not accurate enough to replace laboratory measurement of GFR; and (4) GFR prediction inaccuracy is more often associated with extremes in patient age, weight, serum creatinine, body surface area, and measured GFR but may occur for any value of each of these parameters.     

Age- and sex-dependent clinical equations to estimate glomerular filtration rates in children and young adults with chronic kidney disease

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The relationship between estimated glomerular filtration rate, demographic and anthropometric variables is mediated by muscle mass in non-diabetic patients with chronic kidney disease.

BACKGROUND: In this study (the first of two related papers), we report whether the relationship between the demographic and anthropometric variables (DA, i.e. age, gender, height and weight) employed in current creatinin (Cr)-based glomerular filtration rate (GFR) estimation equations and actual GFR is mediated by muscle mass. METHODS: We studied 77 patients (mean age +/- SD, 65.1 +/- 11.9 years) with chronic kidney disease (mean GFR 45.7 +/- 28.6 ml/min/1.73 m2). Actual GFR was measured by the renal clearance of inulin (GFR(inu)). Appendicular lean mass (ALM) and its index (ALMI) by dual energy X-ray absorptiometry provided markers of muscle mass. Multiple regression analyses identified variables explaining variance in (i) GFR, (ii) ALM and (iii) Cr. RESULTS: (i) The DA variables used in the abbreviated modification of diet in renal disease (MDRD) equation accounted for only 59.6% (P < 0.001) of the variance in GFR(inu), whilst adding ALMI explained an additional 10.4% variance (P < 0.001). If ALMI was entered first, the relationship between DA variables and GFR(inu) was reduced (for weight) or completely abolished (for age, gender and height). (ii) After inputting all the commonly used DA variables, 17.2% of the variance in ALM was unexplained. (iii) All the DA variables explained only 60.6% (P < 0.001) of the variance in Cr, whilst adding ALM explained an additional 4.2% variance (P < 0.005). CONCLUSIONS: Muscle mass explained more variance in GFR(inu) than MDRD DA variables and mediated the relationship between GFR(inu) and DA variables. Furthermore, DA variables failed to account for individual differences in muscle mass or Cr. Consequently, there is a need to validate simpler, clinically obtainable measures of muscle mass and determine whether these measures will improve GFR estimation.     

Validation of the EKFC equation for glomerular filtration rate estimation and comparison with the Asian-modified CKD-EPI equation in Chinese chronic kidney disease patients in an external study

ObjectivesThe aim of this study is to determine whether new European Kidney Function Consortium (EKFC) equation is more applicable than Asian-modified CKD-EPI equation in clinical practice, having a higher accuracy in estimating GFR in our external CKD population.MethodsWe calculated estimated GFR_EKFC and GFR_CKD-EPI independently using the EKFC and Asian-modified CKD-EPI formulas, respectively. The clinical diagnostic performance of the two equations was assessed and compared by median bias, precision, accuracy (P₃₀) and so on, using ^99mTc-DTPA dual plasma sample clearance method as a reference method for GFR measurement (mGFR). The equation that met the following targets was superior: (1) median bias within ± 3 mL/min/1.73 m²; (2) P₃₀ > 75%; and (3) better precision and 95% limits of agreement in Bland–Altman analysis.ResultsTotally, 160 CKD patients were recruited in our external cohort. GFR_EKFC was highly related to mGFR, with a regression equation of GFR_EKFC=mGFR × 0.87 + 5.27. Compared with the Asian-modified CKD-EPI equation, EKFC equation demonstrated a wider median bias (–1.64 vs. 0.84 mL/min/1.73 m², p < 0.01) that was within 3 mL/min/1.73 m² and not clinically meaningful. Furthermore, the precision (12.69 vs. 12.72 mL/min/1.73 m², p = 0.42), 95% limits of agreement in Bland–Altman analysis (42.4 vs. 44.4 mL/min/1.73 m²) and incorrect reclassification index of the two target equations were almost identical. Although, EKFC equation had a slightly better P₃₀ (80.0% vs. 74.4%, p = 0.01).ConclusionsThe overall performance of EKFC equation is acceptable. There is no clinically meaningful difference in the performance of the Asian-modified CKD-EPI and EKFC equations within the limits imposed by the small sample size.     

Lean body mass-adjusted Cockcroft and Gault formula improves the estimation of glomerular filtration rate in subjects with normal-range serum creatinine

BACKGROUND: Assessment of glomerular filtration rate (GFR) in individuals with normal-range serum creatinine is important in certain clinical situations, such as in potential living kidney donors. Accurate measurements of GFR invariably involve using an invasive method (e.g. inulin clearances), but is inconvenient. The aim of the present study was to determine whether serum creatinine-based prediction formulae adjusted for lean body mass (LBM) could improve the accuracy of GFR estimation in these subjects. METHODS: Glomerular filtration rate was determined by the clearance of technetium-99m-labelled diethylenetriamine penta-acetic acid ((99m)Tc DTPA) from plasma in 56 subjects with normal serum creatinine. For each subject, GFR was estimated using prediction formulae +/- LBM adjustment and compared with measured GFR. Formulae analysed include Cockcroft-Gault, Levey, Gates, Mawer, Hull, Toto, Jellife and Bjornsson. RESULTS: All formulae +/- LBM adjustment underestimated measured GFR, with poor precision, poor agreement and correlation (r (2) 相似文献   

Estimation of glomerular filtration rate in South Asian healthy adult kidney donors

Aim:   We evaluated the performance of serum creatinine based equations to estimate glomerular filtration rate (GFR) in South Asian healthy renal donors.
Methods:   GFR by 99mTc-diethylenetriamine pentaacetic acid (DTPA) renogram (mGFR) in 599 renal donors was measured. GFR was estimated using a six variable modification of diet in renal disease formula (MDRD1), a four variable MDRD formula (MDRD2), Cockcroft-Gault creatinine clearance (CG CrCl), Cockcroft-Gault glomerular filtration rate (CG GFR) and the Mayo Clinic formula (Mayo GFR). The performance of various prediction equations was compared for global bias, precision (R²) and accuracy (percentage of estimated GFR (eGFR) falling within 15% and 30% of mGFR).
Results:   The mean age was 37.4 ± 11 years and 48.2% were male. The mGFR was 95.5 ± 11.6 mL/min per 1.73 m². The bias (mL/min per 1.73 m²) was 7.5 ± 0.9, −9.0 ± 0.75, 13.1 ± 0.9, 7.5 ± 0.9 and 23.4 ± 0.76 for CG CrCl, CG GFR, MDRD1, MDRD2 and Mayo GFR, respectively. R² was 0.082 for CG CrCl and MDRD1, 0.081 for CG GFR and MDRD2 and 0.045 for Mayo GFR. The percentages of eGFR falling within 15% and 30% of mGFR were 50.5 and 80.1 for CG CrCl, 65.8 and 84 for CG GFR, 50 and 74 for MDRD1, 54.3 and 80.1 for MDRD2 and 32 and 63.4 for Mayo GFR. Overall CG GFR performed better in estimating GFR in all subjects.
Conclusion:   The CG GFR equation was better than other equations to estimate GFR in South Asian healthy renal donors. We propose a new equation derived from the regression model in our study population to estimate GFR in a South Asian healthy adult population.     

Renal plasma flow and glomerular filtration rate duringacute kidney injury in man

During acute kidney injury (AKI), lowered glomerular filtration rate (GFR) is believed to be consequent to reduced renal plasma flow (RPF). We aimed to systematically evaluate the evidence for such an association. Using specific search terms, we systematically interrogated the Pub Med electronic reference database for studies of human AKI where renal plasma or blood flow and GFR were measured; older articles were then identified by screening bibliographies of retrieved reports. We identified 22 articles describing 250 patients (203 native kidney, 47 in renal allograft). Of these studies, 8 articles (110 patients) estimated effective renal plasma flow (ERPF) by clearance techniques and 14 articles (140 patients) estimated true renal plasma flow (TRPF). Mean RPF was 272 mL/min (95% CI 213–331) and GFR 13.9 mL/min (9.9–17.9). Mean TRPF was significantly greater than mean ERPF (344 vs. 180, p = 0.004) despite lower mean GFR (8.8 vs. 20.4, p = 0.002). There was no significant association between RPF and GFR between studies. Eleven studies presented individual patient data (76 patients: 49 TRPF, 27 ERPF); here, individual patient ERPF was associated with GFR (r² = 0.52), but TRPF was not. During AKI in man, there is only a limited association between ERPF and GFR, and no detectable association between TRPF and GFR.     

Trajectories of glomerular filtration rate and progression to end stage kidney disease after kidney transplantation

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Applicability of a different estimation equation of glomerular filtration rate in Turkey

Abstract

We aimed to investigate the performance of various creatinine based glomerular filtration rate estimation equations that were widely used in clinical practice in Turkey and calculate a correction coefficient to obtain a better estimate using the isotope dilution mass spectrometry (IDMS)-traceable Modification of the Diet in Renal Disease (MDRD) formula. This cross-sectional study included adult (>18 years) outpatients and in patients with chronic kidney disease as well as healthy volunteers. Iohexol clearance was measured and the precisions and bias of the various estimation equations were calculated. A correction coefficient for the IDMS-traceable MDRD was also calculated. A total of 229 (113 male/116 female; mean age 53.9?±?14.4 years) subjects were examined. A median iohexol clearance of 39.21?mL/min/1.73?m² (range: 6.01–168.47?mL/min/1.73?m²) was found. Bias and random error for the IDMS-traceable MDRD equation were 11.33?±?8.97?mL/min/1.73?m² and 14.21?mL/min/1.73?m², respectively. MDRD formula seems to provide the best estimates. To obtain the best agreement with iohexol clearance, a correction factor of 0.804 must be introduced to IDMS-traceable MDRD equation for our study population.     

Change of glomerular filtration rate in healthy adults with aging

Aim:   In order to determine the relationship between glomerular filtration rate (GFR) and age, the associated factors, and the accurate method of GFR in healthy adults, we conducted a cross-sectional study in community-dwelling adults in Beijing.
Methods:   Renal function of 201 clinically healthy subjects was determined using technetium-99 m-labelled diethylene triamine pentacetic acid (^99mTc-DTPA). Estimated GFR was calculated with the Cockcroft–Gault (CG) equation, abbreviated Modification of Diet in Renal Disease (MDRD) equation, and plasma clearance of creatinine (Ccr). Serum cystatin C, biomarkers of inflammatory and endothelial cells were analyzed as well. Protein intake, carotid artery intima-media thickness and plaque formation were assayed as well.
Results:   Glomerular filtration rate was negatively associated with age and the correlation coefficient for ^99mTc-GFR, CG-GFR, MDRD-GFR, Ccr were −0.643, −0.736, −0.55 and −0.619, respectively ( P  < 0.001), while the correlation coefficient between cystatin C and age was 0.681 ( P  < 0.001). Estimated GFR were associated with measured GFR, and the correlation coefficient for Ccr, CG-GFR and MDRD-GFR were 0.813, 0.582 and 0.418, respectively ( P  < 0.001). The area under the receiver–operator curve of Ccr was larger, CG was smaller while MDRD was the smallest, and the difference was significant ( P  < 0.001). So a predicted equation was presented by cystatin C and C-reactive protein for the elderly.
Conclusion:   In the clinically healthy adults, GFR declined with age. MDRD and CG equation are not suitable to estimate GFR in healthy adults. The predicted equation established by cystatin C and C-reactive protein may be more accurate.     

Simultaneous glomerular filtration rate determination using inulin,iohexol, and 99mTc-DTPA demonstrates the need for customized measurement protocols

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