Residual risk may persist within established chronic kidney disease (CKD) categories, according to a cross-sectional analysis published in BMJ Open Diabetes Research & Care, which evaluated the Fibrosis-4 (FIB-4) index alongside Kidney Disease: Improving Global Outcomes (KDIGO) stratification in patients with type 2 diabetes mellitus (T2DM) and hypertension.

The study included 1,208 patients, with FIB-4 dichotomized at 1.3, as per established thresholds. The primary outcome was KDIGO high/very high risk (categories 3-4), and the secondary outcome was CKD, defined as estimated glomerular filtration rate <60 mL/min/1.73 m² and/or albumin-to-creatinine ratio ≥30 mg/g.

The mean age was 58.3 years, and 60.1% were male. Elevated FIB-4 (>1.3) was observed in 514 patients (42.5%), while 286 (23.7%) were classified as KDIGO 3-4, and 588 (48.7%) met CKD criteria. After multivariable adjustment, FIB-4 >1.3 was associated with higher odds of KDIGO 3-4 (OR 1.57; 95% CI 1.12-2.19; p=0.008) and CKD (OR 1.51; 95% CI 1.14-2.01; p=0.004). These associations were also observed in patients meeting body mass index and low-density lipoprotein cholesterol targets, although statistical power was limited for KDIGO 3-4.

Within KDIGO low-risk categories, higher FIB-4 was associated with a greater prevalence of vascular comorbidities. A non-linear relationship was observed, with a threshold effect near 1.3. Overall, elevated FIB-4 was associated with higher CKD risk categories and comorbidity burden, supporting its role as a complementary marker within KDIGO-based risk stratification.