How Reliable Is Estimation of Glomerular Filtration Rate at Diagnosis of Type 2 Diabetes?

Abstract

OBJECTIVE -The Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) equations previously have been recommended to estimate glomerular filtration rate (GFR). We compared both estimates with true GFR, measured by the isotopic 51 Cr-EDTA method, in newly diagnosed, treatment-naïve subjects with type 2 diabetes.RESEARCH DESIGN AND METHODS -A total of 292 mainly normoalbuminuric (241 of 292) subjects were recruited. Subjects were classified as having mild renal impairment (group 1, GFR Ͻ90 ml/min per 1.73 m 2 ) or normal renal function (group 2, GFR Ն90 ml/min per 1.73 m 2 ). Estimated GFR (eGFR) was calculated by the CG and MDRD equations. Blood samples drawn at 44, 120, 180, and 240 min after administration of 1 MBq of 51 Cr-EDTA were used to measure isotopic GFR (iGFR).RESULTS -For subjects in group 1, mean (ϮSD) iGFR was 83.8 Ϯ 4.3 ml/min per 1.73 m 2 . eGFR was 78.0 Ϯ 16.5 or 73.7 Ϯ 12.0 ml/min per 1.73 m 2 using CG and MDRD equations, respectively. Ninety-five percent CIs for method bias were -11.1 to Ϫ0.6 using CG and -14.4 to -7.0 using MDRD. Ninety-five percent limits of agreement (mean bias Ϯ 2 SD) were Ϫ37.2 to 25.6 and Ϫ33.1 to 11.7, respectively. In group 2, iGFR was 119.4 Ϯ 20.3 ml/min per 1.73 m 2 . eGFR was 104.4 Ϯ 26.3 or 92.3 Ϯ 18.7 ml/min per 1.73 m 2 using CG and MDRD equations, respectively. Ninety-five percent CIs for method bias were -17.4 to -12.5 using CG and -29.1 to -25.1 using MDRD. Ninety-five percent limits of agreement were Ϫ54.4 to 24.4 and Ϫ59.5 to 5.3, respectively.CONCLUSIONS -In newly diagnosed type 2 diabetic patients, particularly those with a GFR Ն90 ml/min per 1.73 m 2 , both CG and MDRD equations significantly underestimate iGFR. This highlights a limitation in the use of eGFR in the majority of diabetic subjects outside the setting of chronic kidney disease. Diabetes Care 30:300 -305, 2007T he prevalence of chronic kidney disease (CKD) continues to escalate at an alarming rate (1-3). In the U.K., the incidence of end-stage renal disease (ESRD) has doubled in the past 10 years and this increase is projected to continue to rise at a rate of 5-8% per annum (2). In the U.S. in 2003, there were 325,000 individuals receiving renal replacement therapy (RRT) at a cost of $18.1 billion per annum, 45% of these were diabetic patients (3). The number receiving RRT in the U.S. is anticipated to double by 2010 (4), clearly producing a significant economic burden. The number of patients with ESRD underestimates the entire burden of CKD. Whole-population screening surveys performed in Europe (5) and the U.S. (6) have identified that between 6 and 11% of this population have a degree of CKD; this number increases to 50 -60% when at risk groups are screened (6).Diabetes is the leading cause of ESRD in developed countries, accounting for 18 and 36% of new cases of RRT in the U.K. and Germany, respectively, in 2001 (7) and 45% of new cases in the U.S. in 2003 (3). Differences in incidence between developed countries are likely a reflection of racial and ethnic mix. In the U.S., ...

Effects of fenofibrate on renal function in patients with type 2 diabetes mellitus: the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) Study

“…A larger study might have revealed other subgroups likely to benefit more from fenofibrate. Renal assessment through inulin and p-amino hippurate clearance is impractical in large trials and estimated GFR has limitations [13]. Nevertheless, comparative temporal within-patient changes in estimated GFR and particularly plasma creatinine in our large sample are likely to remain robust [43].…”

“…Although estimated GFR may underestimate true glomerular filtration rate [13], particularly at >90 ml min Patients were seen at intervals of 4 to 6 months against a background of usual care, and information on treatment toleration and complications was obtained. Urinary albumin and creatinine were measured pre-randomisation (the mean of two first morning samples) and at year 2, year 5 and close-out.…”

“…Greater preservation of estimated GFR with fenofibrate was observed with baseline hypertriacylglycerolaemia (n=169 vs 491 without) alone, or combined with low HDL-cholesterol (n=140 vs 520 without) and reductions of ≥0.48 mmol/l in triacylglycerol over the active run-in period (pre-randomisation) (n=356 vs 303 without). Fenofibrate reduced urine albumin concentrations and hence albumin/creatinine ratio by 24% vs 11% (p<0.001; mean difference 14% [95% CI [9][10][11][12][13][14][15][16][17][18]; p<0.001), with 14% less progression and 18% more albuminuria regression (p<0.001) than in participants on placebo. Endstage renal event frequency was similar (n=21 vs 26, p=0.48).…”

Diabetic Nephropathy: New Risk Factors and Improvements in Diagnosis

“…Several equations have been developed for estimating GFR. The Modified Diet in Renal Disease (MDRD) Study equation underestimates GFR, particularly in patients with GFR >90 ml/min/1.73m 2 [72]. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation appears to be more accurate than the MDRD equation in estimating GFR, particularly at higher GFR [73][74][75].…”

Comparison of Modification of Diet in the Renal Disease (MDRD) and Cockroft-Gault (CG) Formulas for Estimating Glomerular Filtration Rate (GFR) in Patients Metabolic Syndrome

“…In group MS between MDRD and AU we not observed a correlation (p=0.263) Figure 3, but with between CG and AU there was a incorrect positive relationship (p=0.001=) Figure 4. In general, these studies show good performance in people with MS. Two studies, comparing the CG and MDRD formulae to a measured GFR, found that the MDRD formula was more precise and accurate than the CG formula in people with MS (14). In comparing with the normal population, MS is accepted like a independent risk factor for CKD.…”