Bedside Estimation of the Glomerular Filtration Rate in Hospitalized Elderly Patients

Abstract

Aims: To evaluate the quality of bedside estimation of glomerular filtration rate (GFR) in hospitalized elderly patients. Methods: We evaluated common estimators of GFR in 29 women and 32 men aged 60 and older hospitalized in a geriatric ward: creatinine clearance (CCR), the Cockcroft-Gault formula (CG), the modification of diet in renal disease formula (MDRD), Baracskay formula (BAR), and a newly developed formula derived recently by us (GCM). Inulin clearance (CINU) was used to assess GFR. Exclusion criteria were mental illness and urinary incontinence. Results: According to Bland and Altman accuracy and precision of all estimators were low and there was an underestimation of actual GFR: CCR 38.9 ml/min; CG 39.7 ml/min; MDRD 19.8 ml/min; BAR 34.0 ml/min, and GCM: 24.7 ml/min. The accuracy and precision of all methods were even lower in patients with a GFR of >90 ml/min and in patients with diabetes. In receiver-operating characteristics (ROC analysis) all formulas were superior to serum creatinine and overall MDRD disclosed the best results in detecting both a GFR of <90 ml/min and <60 ml/min. Conclusions: In general, estimation errors are large in an acute care setting. However, formula estimation is clearly superior to serum creatinine and CCR. MDRD gave the best results but may be replaced by the more simple CG and GCM formulas, whereas BAR was inferior.

Should We Continue to Use the Cockcroft-Gault Formula?

“…Fehrman-Ekholm et al [14] did not report a statistical tool other than the coefficients of correlation and of determination. Burkhardt et al [13] did not adequately explain their very large SD of the ME (the largest one found in our review) obtained using both MDRD and CG. This large value led us to question the precision of the gold standard in their study; it was the only study that used one shot of inulin rather than a constant perfusion as a gold standard.…”

“…We found 3 articles [4,13,14] that compared estimations using MDRD and CG to a gold standard in elderly populations. Additionally, a subgroup aged >65 years was extracted from Froissart et al [23] (table 5).…”

“…Studies were included if they contained a gold-standard GFR measure, such as inulin or isotopic methods. We typically compared CG with the abbreviated 4-variable MDRD formula; however, in 6 articles [4,5,12,13,14,15,16] only the 6-variable MDRD formula was reported. Since the 2 MDRD formulas have relatively similar accuracies [1], we do not expect that the use of both the 4- and 6-variable formulas is a major limitation.…”

“…CrCl estimated by CG as well as measured and estimated GFRs were adjusted for body surface area and expressed in ml/min/ 1.73 m 2 in all but 4 articles [4,5,13,26]. In statistical tables, an empty cell indicates that information was not reported.…”

Stability of plasma creatinine concentrations in acute complex long-stay admissions to a general medical service

“…During acute illness, patients are more likely to experience short-term fluctuations in renal function. 9 In the original study by Cockcroft and Gault, the authors recruited participants ranging in age from 18 to 92 years. In total, 534 participants were recruited and two creatinine clearances were determined.…”