Estimation of glomerular filtration rate in the elderly: a comparison of creatinine-based formulae with serum cystatin C

OBJECTIVES: To estimate the prevalence of decreased kidney function in an elderly population and to evaluate the impact of using alternative markers of glomerular filtration rate (GFR), focusing on serum cystatin C (Cys C) and the Modification of Diet in Renal Disease (MDRD) Study prediction equation. DESIGN AND METHODS: In a cross-sectional community-based survey renal function was assessed by serum creatinine (SCreat), Cys C and GFR predicted by the Cockcroft-Gault (CG) and the MDRD Study formulae. Associations with age, gender and proteinuria were analysed by linear models. SUBJECTS: A total of 1246 elderly residents in Lieto, Finland, 64-100 years of age. RESULTS: The prevalence of moderately or severely decreased renal function, estimated by the MDRD Study equation, was 35.7%; the CG formula yielded 58.6%. The profile of Cys C performance, including variation across age groups and level of health status, showed greater similarity to GFR estimated using the MDRD Study equation than to SCreat alone, or GFR estimated using the CG formula. Discordance between high Cys C levels and only mildly decreased GFR estimates was observed in subjects with functional limitations. Microalbuminuria was associated with Cys C levels only (P =0.047). CONCLUSION: Prevalence estimates of decreased renal function amongst the elderly vary considerably depending on prediction formula used. Variation in creatinine metabolism amongst elderly comorbid patients and the critical dependence on the SCreat assay and exact calibration, make the use of creatinine-based formulae to predict GFR questionable in geriatric clinical practice. In this setting, Cys C is a promising alternative.     

三种不同肾功能评估方法对冠状动脉旁路移植术后死亡的预测

目的 比较三种不同肾功能评估方法对冠状动脉旁路移植术后死亡的预测作用.方法 回顾分析1999年1月至2005年12月收治的5559例冠状动脉旁路移植术患者的资料.以患者术前72 h内空腹血清肌酐值、Cockeroft-Gault公式和简化MDRD公式计算的估测肾小球滤过率作为肾功能的评估方法.通过受试者工作特征(ROC)曲线、Cox比例风险回归分析,比较三种不同肾功能评估方法对冠状动脉旁路移植术后死亡的预测作用.结果 ROC曲线分析显示,CoekcroftGault公式预测住院死亡的准确性最高(ROC曲线下面积:0.755,P＜0.01).Cox比例风险回归分析显示:Cockerofi-Gault公式估测肾小球滤过率对住院死亡的预测作用最高[相对危险度(HR):4.51,P＜0.01],优于简化MDRD公式估测肾小球滤过率(HR:3.43,P＜0.01)和血清肌酐(HR:2.86,P＜0.01);Cockerofi-Gault公式估测肾小球滤过率(HR:1.54,P＜0.01)和简化MDRD公式估测肾小球滤过率(HR:1.60,P＜0.01)对远期死亡的预测作用均优于血清肌酐(HR:1.40,P=0.11).结论 术前肾功能不全是冠状动脉旁路移植术后死亡的独立危险因素.Cockcroft-Gault公式估测肾小球滤过率对住院死亡的预测作用优于简化MDRD公式估测肾小球滤过率和血清肌酐,Cockcroft-Gault公式估测肾小球滤过率和简化MDRD公式估测肾小球滤过率对远期死亡的预测作用均优于血清肌酐.     

Chronic kidney disease in Japan

Chronic kidney disease (CKD) is defined as either kidney damage with urine, imaging, and histologic abnormalities, or a low estimated glomerular filtration rate (GFR) for more than 3 months. The GFR is calculated using either the Modification of Diet in Renal Disease (MDRD) Study equation or the Cockcroft-Gault formula. CKD is a risk factor for end-stage renal disease (ESRD) and cardiovascular disease. In Japan, the prevalence of ESRD is increasing and is currently more than 2,000 per million population. More than 40% of incident ESRD is due to diabetes mellitus (DM). The prevalence of a low GFR (< 60 ml/min/1.73 m(2)) is estimated to be 20% of the adult population. Studies based on several community-based screening programs suggest that Japan has a higher prevalence of CKD than any other country. Early detection and treatment of CKD are necessary to decrease the incidence of ESRD and cardiovascular disease.     

Is Modification of Diet in Renal Disease formula similar to Cockcroft-Gault formula to assess renal function in elderly hospitalized patients treated with low-molecular-weight heparin?

BACKGROUND: Repeated administration of low-molecular-weight heparin (LMWH) to elderly patients with an impaired renal function may lead to an accumulation effect with an increased risk of bleeding. In this setting, Cockcroft-Gault (CG) is the most widely used formula for glomerular filtration rate (GFR) estimation. In hospitalized patients over the age of 70, the six-variable Modification of Diet in Renal Disease (MDRD) formula was compared with the CG formula to detect patients with renal impairment who are at higher risk of bleeding when treated with LMWH. METHODS: We combined retrospective data from 366 patients aged 86.2 +/- 6.6 years, treated with LMWHs. CG and MDRD GFR estimates were compared using the Bland-Altman method and the agreement between the two formulae by the kappa coefficient. RESULTS: The mean CG and MDRD estimated GFR were 45.9 +/- 21.9 mL/min and 75.6 +/- 32.6 mL/min/1.73 m(2), respectively, with a mean bias of 29.6 mL/min. The concordance between the formulae to classify patients into stages of kidney disease was very poor (weighted kappa = 0.17): 21.8% patients had severe renal function impairment with the CG formula versus 1.3% with the MDRD formula. In our population, the MDRD thresholds that would correspond to CG estimates of 30 mL/min and 60 mL/min were found at 63 mL/min/1.73 m(2) and 80 mL/min/1.73 m(2), respectively. CONCLUSIONS: In elderly patients, GFR estimates using MDRD and CG formulae differ widely and identify different numbers of individuals with kidney disease. Prospective comparative studies are needed to validate these formulae and their different thresholds to better detect elderly patients at higher risk of bleeding when treated with LMWH.     

Cockcroft-Gault formula is biased by body weight in diabetic patients with renal impairment

The Cockcroft-Gault (CG) formula and the modification of diet in renal disease (MDRD) equation are commonly used to estimate glomerular filtration rate (GFR), but their validity at extreme body weight is questionable. This may be significant for diabetic patients. In 122 diabetic patients with renal damage, we compared both estimates to isotopically determined GFR by correlation studies and a Bland and Altman procedure before and after categorizing the patients according to body mass index (BMI). Over the whole population, the CG overestimated GFR (CG, 51.4 +/- 23.1 mL/[min . 1.73 m2]; isotopic GFR, 44.6 +/- 21.1 mL/[min . 1.73 m2], P < .0001). The MDRD (45.2 +/- 17.9; NS vs isotopic GFR) did not overestimate GFR, but it underestimated high GFR as revealed by the Bland and Altman procedure (r = -0.26, P < .005). The CG underestimated GFR in patients with normal BMI (-14%, P < .01) and overestimated it in overweight (15%, P < .005) and obese patients (55%, P < .0001); the result and the error of the estimation were correlated with BMI. This bias did not affect the MDRD. The use of ideal instead of measured body weight improved the CG prediction, but underestimated GFR. As the BMI of the 87 type 2 diabetic subjects was higher, the CG overestimated their mean GFR by 18% (P < .001), whereas the MDRD did not. There were 25% fewer patients with delayed referral using the MDRD than with the CG. Because the estimate of GFR by the CG is proportional to body weight, it is not suited for obese diabetic patients. Although it is less easy to calculate, the MDRD is not affected by weight, and its use would avoid delay in referral to nephrologists.     

Renal disease in systemic sclerosis with normal serum creatinine

Prognosis of systemic sclerosis largely depends on involvement of internal organs. The aim was to evaluate renal impairment in patients with systemic sclerosis by measuring the Glomerular filteration rate (GFR) and then calculating the GFR using the Cockgroft and Gault formula and the Modification of Diet in Renal Disease Equation (MDRD) formula. Thirty one scleroderma patients were recruited from the Rheumatology and Rehabilitation Department, Cairo University Hospitals, mean age 43.25 ± 11.28 years, 31 healthy controls were included. Disease severity was done using Medsger score. GFR was measured using classical Gates method TC99mDTPA. The modified Cockcroft and Gault formula and equation 7 from the MDRD were used for calculation of GFR. All patients had within normal serum creatinine levels. A normal GFR (>89ml/min) was found in 45.1%. Gates method showed reduced GFR was reported in 54.9%. Stage II chronic kidney disease (60-89 ml/min) found 32.3%, and stage III (30-59 ml/min) in 22.6%. The formulae used showed reduction of GFR in 35.29% of those affected by the Cockcroft-Gault and in 41.17% of those affected using the MDRD. No correlation to patients’ age, disease duration, or severity. A positive correlation was also reported between the presence of renal involvement and pulmonary vascular involvement p = 0.04. Gates method showed reduction of the GFR in 54.9% of the systemic sclerosis patients. The formulae used were not as precise as the measured GFR in diagnosing all cases with subclinical renal involvement. Patients with systemic sclerosis should be screened for renal involvement irrespective of disease severity or duration.     

Prevalence of low glomerular filtration rate, proteinuria and associated risk factors in North India using Cockcroft-Gault and Modification of Diet in Renal Disease equation: an observational, cross-sectional study

Background

Chronic kidney disease (CKD) is increasingly being recognized as an emerging public health problem in India. However, community based estimates of low glomerular filtration rate (GFR) and proteinuria are few. Validity of traditional serum creatinine based GFR estimating equations in South Asian subjects is also debatable. We intended to estimate and compare the prevalence of low GFR, proteinuria and associated risk factors in North India using Cockcroft-Gault (CG) and Modification of Diet In Renal Disease (MDRD) equation.

Methods

A community based, cross-sectional study involving multistage random cluster sampling was done in Delhi and its surrounding regions. Adults ≥ 20 years were surveyed. CG and MDRD equations were used to estimate GFR (eGFR). Low GFR was defined as eGFR < 60 ml/min/1.73 m². Proteinuria (≥ 1+) was assessed using visually read dipsticks. Odds ratios, crude and adjusted, were calculated to ascertain associations between renal impairment, proteinuria and risk factors.

Results

The study population had 3,155 males and 2,097 females. The mean age for low eGFR subjects was 54 years. The unstandardized prevalence of low eGFR was 13.3% by CG equation and 4.2% by MDRD equation. The prevalence estimates of MDRD equation were lower across gender and age groups when compared with CG equation estimates. There was a strong correlation but poor agreement between GFR estimates of two equations. The survey population had a 2.25% prevalence of proteinuria.In a multivariate logistic regression analysis; age above 60 years, female gender, low educational status, increased waist circumference, hypertension and diabetes were associated with low eGFR. Similar factors were also associated with proteinuria. Only 3.3% of subjects with renal impairment were aware of their disease.

Conclusion

The prevalence of low eGFR in North India is probably higher than previous estimates. There is a significant difference between GFR estimates derived from CG and MDRD equations.These equations may not be useful in epidemiological research. GFR estimating equations validated for South Asian populations are needed before reliable estimates of CKD prevalence can be obtained. Till then, primary prevention and management targeted at CKD risk factors must play a critical role in controlling rising CKD magnitude. Cost-benefit analysis of targeted screening programs is needed.     

Prediction of cardiovascular outcome by estimated glomerular filtration rate and estimated creatinine clearance in the high-risk hypertension population of the VALUE trial

BACKGROUND: Reduced renal function is predictive of poor cardiovascular outcomes but the predictive value of different measures of renal function is uncertain. METHODS: We compared the value of estimated creatinine clearance, using the Cockcroft-Gault formula, with that of estimated glomerular filtration rate (GFR), using the Modification of Diet in Renal Disease (MDRD) formula, as predictors of cardiovascular outcome in 15 245 high-risk hypertensive participants in the Valsartan Antihypertensive Long-term Use Evaluation (VALUE) trial. For the primary end-point, the three secondary end-points and for all-cause death, outcomes were compared for individuals with baseline estimated creatinine clearance and estimated GFR < 60 ml/min and > or = 60 ml/min using hazard ratios and 95% confidence intervals. Coronary heart disease, left ventricular hypertrophy, age, sex and treatment effects were included as covariates in the model. RESULTS: For each end-point considered, the risk in individuals with poor renal function at baseline was greater than in those with better renal function. Estimated creatinine clearance (Cockcroft-Gault) was significantly predictive only of all-cause death [hazard ratio = 1.223, 95% confidence interval (CI) = 1.076-1.390; P = 0.0021] whereas estimated GFR was predictive of all outcomes except stroke. Hazard ratios (95% CIs) for estimated GFR were: primary cardiac end-point, 1.497 (1.332-1.682), P < 0.0001; myocardial infarction, 1.501 (1.254-1.796), P < 0.0001; congestive heart failure, 1.699 (1.435-2.013), P < 0.0001; stroke, 1.152 (0.952-1.394) P = 0.1452; and all-cause death, 1.231 (1.098-1.380), P = 0.0004. CONCLUSION: These results indicate that estimated glomerular filtration rate calculated with the MDRD formula is more informative than estimated creatinine clearance (Cockcroft-Gault) in the prediction of cardiovascular outcomes.     

A simplified Cockcroft-Gault formula to improve the prediction of the glomerular filtration rate in diabetic patients

AIM: The National Kidney Foundation recommends stratification of renal failure into moderate (Glomerular Filtration Rate: GFR = 30-60 mL/min/1.73 m2), severe (15-30) or terminal (<15) using the Cockcroft-Gault (CG) or the Modification of Diet in Renal Disease (MDRD) equations. We studied the biases in these methods in an attempt to improve the standard CG (MCG) and devise a strategy for stratification. METHODS: GFR was measured by 51Cr-EDTA clearance in 200 diabetic patients: 100 (Group 1: study of concordance) before 2003 and 100 thereafter (Group 2: validation of MCG). The CG was modified by replacing body weight by its mean value: 76. RESULTS: In group 1, the recommended equations only correctly stratified 50 patients. The CG, not the MDRD, underestimated GFR if BMI was normal, and overestimated it in obese patients. In group 2, the MCG was well correlated with GFR and not biased by weight. Over the whole population, the MCG and MDRD were more accurate for the diagnosis of moderate and severe renal failure. The MDRD showed the lowest differences with GFR, except if GFR > 60, where the MCG performed better. All formulae overestimated low GFR, the MDRD also underestimated high GFR. The best stratification (147/200) was obtained using the MCG if creatininemia < 120 micromol/l and the MDRD if creatininemia > or =120 micromol/l. CONCLUSION: The CG is biased by weight, the MCG corrects this. The more accurate MDRD cannot be used in all patients as it underestimates high GFR. The best stratification was obtained using the MCG at low and the MDRD at high creatininemia.     

Plasma homocysteine and microvascular and macrovascular complications in type 1 diabetes: a cross-sectional nested case-control study

OBJECTIVES. To examine the independent relationship between plasma total homocysteine (tHcy) and microvascular and macrovascular complications. DESIGN. We performed a cross-sectional nested case-control study from the EURODIAB Prospective Complications Study. SETTING. A hospital-based multicentre study at 24 centres in 13 European countries. SUBJECTS. A total of 533 type 1 diabetic patients, diagnosed at <36 years of age. Cases (n=359) were defined as those with one or more complications of diabetes and control subjects (n=174) were all those with no evidence of any complication. Main outcome measures. Retinopathy, albumin excretion rate (AER), glomerular filtration rate (GFR) estimated by Cockcroft-Gault formula, hypertension and cardiovascular disease (CVD) were assessed. RESULTS. In unadjusted models, tHcy (per 5 micromol L(-1)) was significantly associated with nonproliferative retinopathy (OR=1.45, 95% CI: 1.10-1.91), proliferative retinopathy (OR=1.74, 95% CI: 1.34-2.27), macroalbuminuria (OR=1.90, 95% CI: 1.49-2.42), hypertension (OR=2.23, 95% CI: 1.69-2.93) and CVD (OR=1.59, 95% CI: 1.18-2.14). In multivariate models, tHcy was significantly related to macroalbuminuria (OR=1.66, 95% CI: 1.24-2.24) and hypertension (OR=1.57, 95% CI: 1.19-2.07), independent of age, sex, diabetes duration, GFR, microvascular and macrovascular complications and cardiovascular risk factors. There was a significant relationship between tHcy and decreased GFR, independent of established risk factors. The relationship between tHcy and retinopathy was not independent of albuminuria or GFR. The initial positive relationship with CVD was explained by cardiovascular risk factors. CONCLUSION. In this large study of European type 1 diabetic subjects, increased concentrations of tHcy were independently related to macroalbuminuria, renal function and hypertension, which suggests that tHcy might play an important role in the pathogenesis of vascular complications in type 1 diabetes.     

Serum cystatin C concentration compared with other markers of glomerular filtration rate in the old old

OBJECTIVES: To assess serum cystatin C, compared with other markers of renal function, as a marker of renal function in the old old (aged 85 and older). DESIGN: A cross-sectional analysis of data obtained in medically stable people aged 70 and older in a geriatric ward at a university hospital. SETTING: University hospital in Belgium. PARTICIPANTS: Forty-eight patients (17 men, 31 women) mean age +/- standard deviation 84.4 +/- 6.3 without acute illness or overt malignancy 7 days after admission were included. Twenty-five patients were aged 85 and older. MEASUREMENTS: Blood samples and 24-hour urine collections were obtained from each patient to determine serum creatinine, serum cystatin C levels, serum albumin, and creatinine clearance. Glomerular filtration rate (GFR) was estimated using the Cockcroft-Gault formula and the Modification of Diet in Renal Study Group (MDRD) formula. On the same day, clearance of 51chromium ethylenediamine tetraacetic acid was performed in all patients as the criterion standard of GFR. RESULTS: Serum creatinine (r=0.68), serum cystatin C (r=0.62), urinary creatinine clearance (r=0.57), the Cockcroft-Gault formula (r=0.82), and the MDRD-formula (r=0.65) correlated significantly with GFR (P <.0001). Regression analysis showed that serum cystatin C and serum creatinine were comparable markers of renal function (Y=0.442 +/- 0.007 x GFR and Y=0.494 +/- 0.01 x GFR respectively). Receiver operating characteristic analysis showed a similar area under the curve for serum cystatin C and serum creatinine (P=.5) in detecting renal impairment (GFR <80 mL/min). The Cockcroft-Gault formula provides a good estimation of GFR when the GFR is less than 60 mL/min (Y=1.11 +/- 1.04 x GFR). When the GFR is greater than 60 mL/min, the Cockcroft-Gault formula underestimates GFR (Y=11.01 +/- 0.66 x GFR). In patients aged 85 and older, a slight decrease in GFR (51.8 +/- 21.3 mL/min vs 65.2 +/- 34.3 mL/min in patients aged 70-84; P=.10) is observed. This is reflected by a nonsignificant increase in serum cystatin C (P=.06), whereas serum creatinine is identical in both groups (P=.88). CONCLUSION: Serum cystatin C, serum creatinine, the Cockcroft-Gault formula, the MDRD formula, and urinary creatinine clearance are comparable markers of renal function in the overall older population. The Cockcroft-Gault formula underestimates renal function in older people with GFR greater than 60 mL/min. In our study, serum cystatin C was not superior to serum creatinine in the detection of renal impairment.     

Serum creatinine in patients with advanced liver disease is of limited value for identification of moderate renal dysfunction: are the equations for estimating renal function better?

BACKGROUND: The Cockcroft-Gault formula (CGF) is used to estimate the glomerular filtration rate (GFR) based on serum creatinine (Cr) levels, age and sex. A new formula developed by the Modification of Diet in Renal Disease (MDRD) Study Group, based on the patient's Cr levels, age, sex, race and serum urea nitrogen and serum albumin levels, has shown to be more accurate. However, the best formula to identify patients with advanced liver disease (ALD) and moderate renal dysfunction (GFR 60 mL/min/1.73 m2 or less) is not known. The aim of the present study was to compare calculations of GFR, using published formulas (excluding those requiring urine collections) with standard radionuclide measurement of GFR in patients with ALD. METHODS: Fifty-seven consecutive subjects (40% women) with a mean age of 50 years (range 16 to 67 years) underwent 99m-technetium-diethylenetriamine pentaacetic acid (99mTc-DTPA) (single injection) radionuclide measurement of GFR. To calculate GFR, three formulas were used: the reciprocal of Cr multiplied by 100 (100/Cr), the CGF and the MDRD formulas. Pearson's correlation coefficient (r) and Bland-Altman analyses of agreement were used to analyze the association between 99mTc-DTPA clearance and the three equations for GFR. RESULTS: The mean 99mTc-DTPA clearance was 83 mL/min/1.73 m2 (range 28 mL/min/1.73 m2 to 173 mL/min/1.73 m2). Mean calculated GFRs by 100/Cr, the CGF and the MDRD formula were 106 mL/min/1.73 m2, 98 mL/min/1.73 m2 and 86 mL/min/1.73 m2, respectively. Regression analysis showed good correlation between radionuclide GFR and calculated GFR with r(100/Cr)=0.74, r(CGF)=0.80, r(MDRD)=0.87, all at P > or = 0.0001. The MDRD formula provided the least bias. The Bland-Altman plot showed best agreement between GFR calculated by the MDRD formula and 99mTc-DTPA clearance, with only 3 mL/min/1.73 m2 overestimation. There was higher variability between radionuclide GFR and calculated GFR by the CGF and by 100/Cr. Although there was no difference in precision, GFR calculated by the MDRD formula had the best overall accuracy. The sensitivity and specificity for detection of moderate renal dysfunction by the MDRD formulas were 73% and 87%, respectively. CONCLUSIONS: Among the Cr-based GFR formulas, the MDRD formula showed a larger proportion of agreement with radionuclide GFR in patients with ALD. In clinical practice, the MDRD is the best formula for detection of moderate renal dysfunction among those with ALD.     

Association between cigarette smoking and chronic kidney disease in Japanese men.

Cigarette smoking may affect urinary albumin excretion and the glomerular filtration rate in both diabetic and nondiabetic subjects. Here we investigated the association between smoking and decreased or elevated glomerular filtration rate (GFR) and albuminuria by analyzing data from 7,078 Japanese men who had undergone a general health screening between 2005 and 2006. GFR was estimated with the Modified Diet in Renal Disease (MDRD) equation, and low estimated GFR (eGFR) and elevated eGFR were defined, respectively, as eGFR<60 and >90.7 mL/min/1.73 m2. Albuminuria was considered present when the urinary albumin excretion ratio (UAER), expressed as mg/g creatinine, was >or=30 mg/g. Multivariate logistic regression analysis showed that current smoking was associated inversely with low eGFR, and positively with albuminuria and elevated eGFR. The association between current smoking and low or elevated GFR was dependent on the number of cigarettes smoked per day. Former smoking was also significantly inversely associated with low eGFR, but the association between former smoking and albuminuria or elevated eGFR was not significant, even in individuals who had stopped smoking less than 1 year before. These data suggest that cigarette smoking may increase the prevalence of albuminuria and elevated eGFR or hyperfiltration, traits that might be reversed by smoking cessation. Although this concept should be verified by future longitudinal studies, our data suggest that we may need to take into account an individual's smoking status when assessing the presence or absence of chronic kidney disease because cigarette smoking may transiently increase eGFR.     

肾小球滤过率评估方程对老年慢性肾脏病患者适用性的评价

目的 评价肾小球滤过率(GFR)评估方程在老年慢性肾脏病(CKD)患者的适用性.方法 选择老年CKD患者103例,采用Cockcroft-Gauh(CG)方程、MDRD1方程、简化MDRD方程、Jelliffe1973(JE73)方程、Mawer(MA)方程、Hull(HU)方程、Jellife1971(JE71)方程、血肌酐倒数公式,Gate(GA)方程、Bjornsson(BJ)方程,分别预测GFR值,与""Tc DTPA肾动态显像检测的GFR(sGFR)进行比较. 结果 Bland-Ahman分析显示,CG方程、BJ方程和HU方程估计的GFR与sGFR的一致性较好,但所有各方程估计的GFR与sGFR的一致性限度均超过事先规定的专业界值.线性回归结果 显示,JE方程和CG方程估测的GFR与X轴的斜率较其他方程更接近0,MDRD1方程较其他方程有较小的偏差;在所有方程中,BJ方程、JE方程和CG方程GFR符合率较高.在CKD的不同分期中,BJ方程、CG方程和JE方程具有较小的偏差和更优的准确性. 结论 当血肌酐的测定方法 为酶法时,如果直接应用目前临床常用的GFR评估方程预测老年CKD患者的GFR,可能会产生明显的偏差.J方程和HU方程估计的GFR与sGFR的一致性较好,但所有各方程估计的GFR与sGFR的一致性限度均超过事先规定的专业界值.线性回归结果 显示,JE方程和CG方程估测的GFR与X轴的斜率较其他方程更接近0,MDRD1方程较其他方程有较小的偏差;在所有方程中,BJ方程、JE方程和CG方程GFR符合率较高.在CKD的不同分期中,BJ方程、CG方程和JE方程具有较小的偏差和更优的准确性. 结论 当血肌酐的测定方法 为酶法时,如果直接应用目前临床常用的GFR评估方程预测老年CKD患者的GFR,可能会产     

肾小球滤过率评估方程在慢性肾脏病不同分期中的适用性

目的评价肾小球滤过率(GFR)评估方程在慢性肾脏病(CKD)患者不同分期中的适用性。方法选择近一年来在我院肾科就诊的CKD患者,将MDRD7方程、简化MDRD方程、Cockcroft Gault方程估计的GFR值用体表面积(BSA)标准化(7GFR、aGFR、cGFR),与BSA标准化的双血浆法99mTc DTPA测的GFR(sGFR)在不同CKD分期进行比较。结果入选了298例患者,男165例,女133例,年龄(52.5±15.5)岁。引发CKD的病因包括肾小球疾病、梗阻性肾病、肾动脉狭窄、慢性肾小管间质疾病、原因不明或其他疾病。在CKD不同分期,7GFR、aGFR、cGFR与sGFR均有统计学意义(P<0.001)。当sGFR<30ml·min-1·(1.73m2)-1时,7GFR、aGFR和cGFR均显著高于sGFR(P<0.05),sGFR越低,偏差越明显;当sGFR>60ml·min-1·(1.73m2)-1时,7GFR、aGFR和cGFR均显著低于sGFR(P<0.05),sGFR越高,偏差越明显。结论在CKD1、2期,7GFR、aGFR和cGFR过低估计sGFR;在CKD4、5期,过高估计sGFR。上述方程直接应用于我国CKD患者时,可能产生明显的偏差,有必要对其进行适当修正。     

Predicting mortality using two renal function estimation methods in hospitalised stroke patients

The prognostic abilities of the MDRD and Cockcroft-Gault methods for estimating renal function were compared in a cohort study of 1287 patients with acute stroke admitted to a Scottish tertiary care teaching hospital. Using Cox regression analysis corrected for other prognostic variables, both the MDRD and Cockcroft-Gault equations predicted mortality independently of other prognostic factors. A 1 ml/min reduction in GFR as calculated by MDRD was associated with a 1.0% (95% CI: 0.3-1.6) increase in risk of death. A 1 ml/min reduction in creatinine clearance from the Cockcroft-Gault equation was associated with a 1.7% (95% CI: 0.9-2.6) increase in risk of death. The Cockcroft-Gault equation weakly predicted length of stay (r=0.066, p=0.02, Spearman's rank test). In conclusion, both methods independently predict early and late mortality in stroke patients, but the Cockcroft-Gault estimate has greater predictive power in this population.     

The auxiliary table for GFR estimation according to the MDRD formula

The best overall index of renal function is considered to be glomerular filtration rate (GFR) and the gold standard for its assessment is renal inulin clearance (Cin) Unfortunately, Cin cannot be routinely used in daily practice due to its complexity as a test. The most often used ones are the Cockcroft-Gault (CG) formula and the recently developed Modification of Diet in Renal Disease (MDRD) prediction equation. Calculation of MDRD (estimated GFR) according to this formula is simple but it requires a computer program. The following table is prepared for parts of the world where the computer program is not available as yet.     

Accuracy of indirect estimates of renal function in advanced chronic renal failure patients

Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) formula are indirect estimates of renal function which have been widely accepted, though their accuracies have been scarcely validated in advanced chronic renal failure. The purpose of this study was to determine the accuracy (bias and precision) of these formulas in advanced CRF patients. The study group consisted of 99 unselected patients (62 +/- 15 years, 59 females) with advanced CRF. The glomerular filtration rate (GFR) was measured by Tc(99m) DTPA. Simultaneously, estimates of GFR by CG corrected for 1.73 m2 and MDRD (formula 7) were calculated. Agreement was evaluated graphically, bias was assessed by mean and median difference, and precision by median absolute differences and Bland-Altman plots. Mean GFR by DTPA, CG and MDRD were: 16.24 +/- 4.38 and 16.77 +/- 4.65 and 13.58 +/- 4.27 ml/min/1.73 m2, respectively. MDRD equation significantly underestimated GFR-DTPA (p = 0.0001). Both CG and MDRD correlated significantly with GFR-DTPA (R = 0.53 and R = 0.62, respectively). CG formula performed better than the MDRD equation with respect to bias (0.30 vs -3.24 ml/min/1.73 m2, p = 0.0001), and precision (0.58 vs. -3.11 ml/min/1.73 m2, p = 0.0001). By multiple linear regression, the best determinants of the error of the estimation by CC formula were: serum creatinine (beta = -0.58; p < 0.0001), age (beta = -0.62; p < 0.0001), and body mass index (beta = 0.26, p = 0.004), and by MDRD formula were: serum creatinine (beta = -0.38; p < 0.0001), and body mass index (beta = -0.20, p = 0.03). In conclusion, in unselected patients with advanced chronic renal failure, estimates by CC formula were more accurate than those obtained by MDRD formula. Serum creatinine was the main source of error of the estimation of GFR by both formulas, though demographic and anthropometric characteristics influenced as well on their accuracies.     

慢性肾病GFR评估方程的适用性研究

目的评价肾小球滤过率（GFR）评估方程在慢性肾脏病（CKD）患者中的适用性。方法选择123例CKD患者,将Cockcroft—Gault方程、7MDRD方程和简化MDRD方程估算的GFR值用体表面积（BSA）标准化,与BSA标准化的^99mTc-DTPAD测得的GFR在不同CKD分期进行比较。结果与^99mTc—GFR（sGFR）相关性最好的是7MDRD方程,ROC曲线下面积也表明7MDRD方程诊断的工作效率最好。结论建立了用7GFR值推算sGFR理论值的校正式：sGFR=7GFRX1．25—11．72。     

Serum creatinine and creatinine clearance to estimate renal function in essential hypertension

The shortcoming of serum creatinine (SCr) as an index of renal function is well known, patients can have significantly decreased glomerular filtration rates (GFR) with normal range SCr values, making the recognition of renal dysfunction more difficult. This study was designed to estimate renal function and the prevalence of renal dysfunction in essential hypertensive patients, comparing SCr and 4 formulas used to measure the creatinine clearance (CrCl) (the urinary CrCl formula, Cockcroft-Gault, MDRD and body surface formula) The study included 721 essential hypertensive patients, 319 men (44.2%), 402 women (55.8%), mean age 56.3 +/- 13.9 (53.7 +/- 14.4 vs 58.3 +/- 13.3). In all subjects SCr was measured and 24-h urine sample was collected to evaluate CrCl. Creatinine clereance was calculated by 4 formulas. Patients were grouped according to age (< 40, 41-65, 65-75 and > 76) and renal function was classified as normal when SCr < 1.4 in women and 1.5 mg/dl in men and CrCl (> 60 ml/m, respectively) within the above written formulas. SCr increases with age (1.01 +/- 0.36 vs 1.3 +/- 1.15) and CrCl decreases according to the 4 formulas (107.6; 92.8; 74.7 and 57.3 for the urinary SCr formula); (117.7; 87.7; 65.9 and 49.5 for the CC formula); (87.4, 74.9, 66.5 and 61 for the MDRD formula) and (97, 85.3, 71.9 and 57.3 for the body suface formula). The 4 formulas are comparable markers of renal function in the overall population. With any formula the percentage of patients with impaired renal function was much higher than indicated by the plasma creatinine alone (4% for SCr) vs 18.3-25.3% (CrCl < 60 ml/m) according to the 4 formulas. This study documents the substantial prevalence of abnormal renal function in essential hypertension. Estimation of GFR may help to facilitate the early identification of patients with renal impairment.