Clinical and genetic risk factors for progressive fibrosis in metabolic dysfunction-associated steatotic liver disease

Abstract

Background: Fibrosis-4 (FIB4) is a recommended noninvasive test to assess hepatic fibrosis among patients with metabolic dysfunction-associated steatotic liver disease (MASLD). Here, we used FIB4 trajectory over time (ie, "slope" of FIB4) as a surrogate marker of liver fibrosis progression and examined if FIB4 slope is associated with clinical and genetic factors among individuals with clinically defined MASLD within the Million Veteran Program Cohort.

Methods: In this retrospective cohort study, FIB4 slopes were estimated through linear regression for participants with clinically defined MASLD and FIB4 <2.67 at baseline. FIB4 slope was correlated with demographic parameters and clinical outcomes using logistic regression and Cox proportional hazard models. FIB4 slope as a quantitative phenotype was used in a genome-wide association analysis in ancestry-specific analysis and multiancestry meta-analysis using METAL.

Results: FIB4 slopes, generated from 98,361 subjects with MASLD (16,045 African, 74,320 European, and 7996 Hispanic), showed significant associations with sex, ancestry, and cardiometabolic risk factors (p < 0.05). FIB4 slopes also correlated strongly with hepatic outcomes and were independently associated with time to cirrhosis. Five genetic loci showed genome-wide significant associations (p < 5 × 10-8) with FIB4 slope among European ancestry subjects, including 2 known (PNPLA3 and TM6SF2) and 3 novel loci (TERT 5.1 × 10-11; LINC01088, 3.9 × 10-8; and MRC1, 2.9 × 10-9).

Conclusions: Linear trajectories of FIB4 correlated significantly with time to progression to cirrhosis, with liver-related outcomes among individuals with MASLD and with known and novel genetic loci. FIB4 slope may be useful as a surrogate measure of fibrosis progression.

Graphical abstract

FIGURE 1

FIB4 slopes evolve linearly in MASLD. (A) Representative dot plots of FIB4 values over years of clinical follow-up. Slope values derived from linear models are represented by a solid red line and reported in the top right. FIB4 slopes using only first 5 years of data are shown in the red dotted lines. (B) Distribution of FIB4 slope values. (C) QQ plot for distribution showing normality. (D) Distribution of FIB4 slopes by FIB4 baseline <1.3 or 1.3–2.67. (E) Distribution of FIB4 slope values by genetic ancestry. Abbreviations: FIB4, Fibrosis-4; MASLD, metabolic dysfunction–associated steatotic liver disease.

FIGURE 2

Association of FIB4 slopes and clinical outcomes. (A) LOWESS curves showing HR of outcome relative to FIB4 slope. (B) Kaplan-Meier curves of time to clinical outcomes stratified by FIB4 value above or below 0.082 based on the Youden cutpoint. Abbreviation: FIB4, Fibrosis-4.

FIGURE 3

Contribution of FIB4 slope to the clinical prediction of cirrhosis. (A) AUROC curves for prediction of cirrhosis for FIB4 slope (dotted), clinical model (dashed), and combined model (solid). (B) Calibration curves for models shown in (A). (C) Decision curve analysis for models shown in (A). (D) Percentage of χ² of Cox models explained by each predictive variable. Abbreviation: FIB4, Fibrosis-4.

FIGURE 4

Manhattan plot for multiancestry GWAS meta-analysis of FIB4 slope in individuals with MASLD. Significant SNPs on chromosomes 4, 5, 10, 19, and 22 were observed at a threshold p value of 5 × 10⁻⁸. A QQ plot is embedded. Abbreviations: FIB4, Fibrosis-4; GWAS, genome-wide association study; MASLD, metabolic dysfunction–associated steatotic liver disease.