BACKGROUND/AIMS: Several formulas for glomerular filtration rate (GFR) 
estimation, based on serum creatinine or cystatin C, have been proposed. We 
assessed the impact of some of these equations on estimated GFR (eGFR) and 
chronic kidney disease (CKD) prevalence, and on the association with 
cardiovascular risk factors, in a general population sample characterized by a 
young mean age.
METHODS: We studied 1,199 individuals from three Alpine villages enrolled into 
the MICROS study. eGFR was obtained with the 4- and 6-parameter MDRD study 
equations, the Virga equation, and with the three CKD-EPI formulas for 
creatinine, cystatin C, and the combination of creatinine and cystatin C. We 
assessed the concordance between quantitative eGFR levels, CKD prevalence, and 
in terms of association with total, LDL, and HDL cholesterol.
RESULTS: The highest and lowest eGFR levels corresponded to the cystatin C-based 
and MDRD-4 equations, respectively. CKD prevalence varied from 1.8% (Virga) to 
5.8% (MDRD-4). The CKD-EPI based on creatinine showed the highest agreement with 
all other equations. Agreement between methods was higher at lower eGFR levels, 
older age, and in the presence of diabetes and hypertension. Creatinine-based 
estimates of eGFR were associated with total and low-density lipoprotein but not 
high-density lipoprotein cholesterol. The opposite was observed for the cystatin 
C-based GFR.
CONCLUSION: GFR estimation is strongly affected by the chosen equation. 
Differences are more pronounced in healthy and younger individuals. To identify 
CKD risk factors, the choice of the equation is of secondary importance to the 
choice of the biomarker used in the formula. If eGFR is not calibrated to a gold 
standard GFR in the general population, reports about CKD prevalence should be 
considered with caution.