Background: The determination of kidney function is commonly done by estimating the glomerular filtration rate (eGFR) using serum creatinine levels. Various eGFR formulas, including the recently developed European Kidney Function Consortium (EKFC) and the Chronic Kidney Disease Epidemiology Collaboration(CKD-EPI), have been adopted and are commonly utilized in clinical settings. Nevertheless, the extent of acceptance among these formulations in the multi ethnics populace is still undetermined. Thus, this study aimed to evaluate the performance of these formulations across different glomerular filtration rate categories in the adult population.

Methods: The research involved a total of 9,557 individuals (median age of 40 years and 85% being male) who underwent routine medical examinations. Enzymatic or modified Jaffe techniques were employed to measure serum creatinine levels. The CKD-EPI2009 eGFR was employed as corresponding GFR in the comparisons. The Bland–Altman method was used to determine the average discrepancies and 95% confidence intervals of eGFR between each formula. Ultimately, in order to compare the equations, Lin’s correlation coefficients were calculated for various eGFR categories.

Results: The median creatinine level in the different island population showed variability. The CKD-EPI 2009 as well as different equations showed categorical agreement within the range of 91.42 to 92.77%. The correlations between CKD-EPI2009 and CKD-EPI 2021 and EKFC were 0.998 and 0.79, respectively (p < 0.001).

Conclusion: A substantial variation in creatinine and eGFR assessment were observed among different eGFR analysis for the adult population. Prospective study in various clinical contexts using measured GFR is essential to validate eGFR.

Introduction

It is recommended to estimate the glomerular filtration rate (GFR) and albuminuria for assessing renal function and detection of chronic kidney disease (CKD) in adults (1). Furthermore, determining GFR is crucial for monitoring therapy achievement, disease progression, drug dosage, and drug toxicity (2, 3). The substances widely utilized to evaluate GFR are endogenous compounds, particularly creatinine (4). Numerous formulas known to be aimed at estimating GFR (eGFR) by measuring creatinine are used to evaluate renal function. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation 2009 and 2021 (5, 6), and the recently established European Kidney Function Consortium (EKFC) (7) formula are commonly utilized in clinical settings (8).

Several studies have been conducted in Asian countries using their specific demographics to validate eGFR (%9–12). Their respective studies are important since most formulas are generated from European and American-based populations. It was found that the equations exhibited bias in their respective populations. To address this, ethnic coefficients were created to adapt the formula for Modification Diet for Renal Disease (MDRD), and later the CKD-EPI. Asian people exhibit a distinct normal range for creatinine compared to Caucasian populations, potentially because to variations in muscle mass, food, genetics, and other factors (9, 13).

Indonesia, an archipelagic country with five main islands, is home to diverse ethnic characteristics that may have the potential to impact serum creatinine levels, which in turn will influence the use of the eGFR formula. While previous studies have compared eGFR equations in other Asian populations, no prior research has systematically evaluated the performance of CKD-EPI 2009, CKD-EPI 2021, and EKFC in the Indonesian population. Given Indonesia’s unique demographic and ethnic diversity, assessing the applicability of these equations is crucial. This study provides the first large-scale comparison of these formulas in an Indonesian cohort, offering new insights into their performance and potential limitations in this specific population.