Should the CKD EPI Equation Be Used for Estimation of the Glomerular Filtration Rate in Obese Subjects?

INTRODUCTION

The pandemic of obesity is strongly related to increase of chronic kidney disease (CKD) prevalence. The currently recommended CKD epidemiology collaboration (CKD EPI) equation has several serious limitations, particularly in obese subjects who have high body surface area (BSA). The aim of our study was to analyze differences in the prevalence of CKD between CKD EPI and de-indexed equations where individual BSA was used.

METHODS

In a total of 2,058 subjects (random sample from a general rural population, 29.65% obese), BSA was estimated using DuBois and DuBois and Moesteller equations and included into the de-indexed equations (CKD DBi, CKD Mi). CKD was classified according to the KDIGO guidelines, and glomerular hyperfiltration (GHF) was defined as 95th percentile, according to the gender and age decade.

RESULTS

In obese subjects, prevalence of CKD was significantly higher with CKD EPI than with CKD DBi and CKD Mi equations (9.5%, 6.1%, 5.3%, respectively; p < 0.001), while prevalence of GHF was significantly lower (3.8%, 12.3%, 12.8%, respectively; p < 0.001). Opposite results were observed in subjects with a body mass index <25 kg/m2 for CKD (5%, 7.1%, 7.2%; p = 0.07) and GHF prevalence (6.1%, 1%, 0.6%; p < 0.001).

DISCUSSION/CONCLUSIONS: The prevalence of CKD is overestimated, and the prevalence of GHF is underestimated in obese subjects using the CKD EPI equation, i.e., the CKD EPI equation is unreliable in one-third of the population. De-indexed equations should be recommended instead of the CKD EPI equation in epidemiological studies until direct measurement of the glomerular filtration rate becomes more available.