Cross-sectional and longitudinal associations between fatty liver index and kidney function using updated MASLD and CKD–EPI 2021 definitions - a population-based study with region-specific cutoffs

Sep 30, 2026

The updated MASLD framework emphasizes systemic consequences of hepatic steatosis, including kidney dysfunction. The study evaluates both cross-sectional and 5-year longitudinal links between Fatty Liver Index (FLI) and eGFR, and between MASLD and chronic kidney disease (CKD), using region-specific FLI cutoffs and the 2021 CKD–EPI equation. It analyzes 9,911 adults from the Fasa Adults Cohort Study, adjusts for extensive confounders, and performs subgroup and sensitivity analyses to test robustness.

LanguageEnglish

CategoryResearch & Report

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Pages18

Reading Time45 min

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Abstract

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Methods

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Bazmi etal. European Journal European Journal of Medical Research (2026) 31:42 [https://doi.org/10.1186/s40001-025-03645-6](https://doi.org/10.1186/s40001-025-03645-6 of Medical Research)[ of Medical Research](https://doi.org/10.1186/s40001-025-03645-6 of Medical Research) RESEARCH Open Access Cross-sectional and longitudinal associations between fatty liver index and kidney function using updated MASLD and CKD–EPI 2021 definitions: a population-based study with region-specific cutoffs Sina Bazmi 1,2 , Mohammadreza Fardaei2, Reza Homayounfar 1,3, Maryam Kazemi 1, Babak Pezeshki1,4, Reza Malekzadeh5, Nasrollah Ghahramani6,7 and Mojtaba Farjam 1* Abstract Background The updated metabolic dysfunction-associated steatotic liver disease (MASLD) framework highlights the systemic impact of hepatic steatosis, including kidney dysfunction. We investigated both cross-sectional and 5-year longitudinal associations between Fatty Liver Index (FLI) and estimated glomerular filtration rate (eGFR), and between MASLD and Chronic kidney disease (CKD), using region-specific FLI cutoffs and the latest definitionsand robust methodology. Methods We analyzed 9,911 adults from the Fasa Adults Cohort Study (FACS), including 2,906 with 5-year followup. FLI was calculated using sex-specific regionally validated cutoffs. eGFR was estimated using the 2021 CKD–EPI equation. Regression models assessed continuous FLI–eGFR and binary MASLD–CKD associations, with scatter plots to visualize patterns. Models were adjusted for extensive confounders. Subgroup analyses were stratified by sex, obesity, and physical activity, with formal interaction testing. Sensitivity analyses applied the commonly used European FLI ≥ 60 threshold. Results Cross-sectionally, MASLD was associated with 58% higher odds of CKD (OR = 1 . 58; 95% CI 1.35–1. 85), and each ten-unit increase in FLI was associated with a 2.4 mL/min/1 .73 m2 lower eGFR (p < 0. 001) . A U-shaped FLI– eGFR association was detected, most prominent in men. Longitudinally, higher FLI predicted greater eGFR decline (β = −1 . 92; p = 0 . 005) and MASLD increased CKD risk (OR = 1 .41; 95% CI 1.07–1. 86), especially among males (OR = 2 . 27), non-obese (OR = 1 .47) and physically active individuals (OR = 1 . 64) . Subgroup differences by obesity and physical activity were descriptive only, as interaction terms were not significant (p > 0. 05) . Using FLI ≥ 60, cross-sectional results remained significant, whereas longitudinal associations attenuated, suggesting potential misclassification when nonpopulation-specific cutoffs are applied. Conclusions Higher FLI and MASLD were associated with impaired kidney function cross-sectionally and prospectively. Region-specific FLI cutoffs resulted in more stable longitudinal associations than the European FLI ≥ 60 *Correspondence: Mojtaba Farjam [Farjam.phd@gmail.com](Farjam.phd@gmail.com) Full list of author information is available at the end of the article © The Author(s) 2025. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit [http://creativ

FAQs

What was the study aim regarding fatty liver and kidney function?

To assess both cross-sectional and 5-year longitudinal associations between Fatty Liver Index (FLI) and eGFR, and between MASLD and CKD using updated definitions and region-specific FLI cutoffs.

How were eGFR and FLI measured in the study?

eGFR was estimated with the 2021 CKD–EPI equation, and FLI was calculated using sex-specific regionally validated cutoffs.

What were the main findings about the relationship between MASLD/FLI and CKD?

Cross-sectionally, MASLD showed higher odds of CKD and each 10-unit increase in FLI corresponded to lower eGFR; longitudinally, higher FLI predicted greater eGFR decline and increased CKD risk, with some subgroup differences and sensitivity effects depending on the cutoff used.

Sep 30, 2026

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