Formula estimation of glomerular filtration rate: have we gone wrong?

Abstract

Paul D Giles and David A Fitzmaurice argue that the introduction of estimated glomerular filtration rate to screen for chronic kidney disease in primary care will lead to pressure on specialist services and create patient anxiety without clear proof of benefit

Fig 1 Association of estimated glomerular filtration rate (GFR) with GFR measured by an isotopic reference method. Below 60 ml/min/1.73 m² the two methods are tightly associated, with limited scatter of the points. At higher filtration rates scatter becomes progressively worse, and in kidney donors estimated GFR underestimates renal function compared with reference measurements. Adapted from Poggio et al

Fig 2 Scatter plot of estimated glomerular filtration rate (GFR) against isotopic reference GFR in subjects with normal serum creatinine using two different creatinine assays (enzymatic and Jaffe methods). Formula calculations underestimate GFR for both assays. The negative bias is less with the enzymatic assay, but the scatter of results is wide with both methods. Adapted from Verhave et al