Elevated FIB-4 index as a risk marker within the KDIGO framework in patients with type 2 diabetes and hypertension

BACKGROUND AND AIMS: The Kidney Disease: Improving Global Outcomes (KDIGO) 2024 guideline recommends risk stratification for chronic kidney disease (CKD) management; however, patients within the same KDIGO category may still experience heterogeneous outcomes. Hypertension and type 2 diabetes mellitus (T2DM) are predominant causes of CKD, and hepatic fibrosis is highly prevalent in this population, but not integrated into current KDIGO risk assessment. The Fibrosis-4 (FIB-4) index, a widely validated noninvasive marker of hepatic fibrosis, may capture residual risk not reflected by KDIGO stratification. This study aims to explore whether FIB-4 can identify residual risk beyond KDIGO stratification in patients with T2DM and hypertension. METHODS: This cross-sectional study included 1208 patients with T2DM and hypertension. FIB-4 was dichotomized at 1.3 based on established guidelines. The primary outcome was KDIGO high/very high risk (categories 3-4). The secondary outcome was CKD, defined as an estimated glomerular filtration rate <60 mL/min/1.73 m² and/or albumin-to-creatinine ratio ≥30 mg/g. Multivariable logistic regression, restricted cubic spline analysis, and stratified analyses were conducted. RESULTS: Among 1208 patients (mean age 58.3 years; 60.1% male), 514 (42.5%) had FIB-4>1.3, 286 (23.7%) were classified as KDIGO 3-4, and 588 (48.7%) met criteria for CKD. After multivariable adjustment, FIB-4>1.3 was independently associated with both KDIGO 3-4 (OR 1.57, 95% CI 1.12 to 2.19, p=0.008) and CKD (OR 1.51, 95% CI 1.14 to 2.01, p=0.004). In stratified analyses, these associations persisted among patients achieving body mass index/low-density lipoprotein cholesterol targets, although statistical power was limited for KDIGO 3-4. Within KDIGO low-risk categories, elevated FIB-4 was associated with a significantly higher prevalence of vascular comorbidities (p value for trend<0.01 for all). Restricted cubic spline modeling demonstrated a non-linear relationship, with a threshold effect at approximately 1.3 (p value for non-linearity<0.001 for KDIGO 3-4; p=0.010 for CKD). CONCLUSIONS: Elevated FIB-4 is independently associated with KDIGO 3-4 and CKD, and identifies patients with higher vascular comorbidity burden even within KDIGO low-risk categories. FIB-4 may serve as a complementary risk stratification marker within the KDIGO framework for patients with T2DM and hypertension.