Association Between the Chinese Visceral Adiposity Index-Frailty Index (CVAI-FI) and the Incidence of New-Onset Stroke in Individuals with Cardiovascular-Kidney-Metabolic Syndrome Stage 0–3: Evidence From a National Population-Based Study

Objective: Cardiovascular-Kidney-Metabolic (CKM) syndrome represents a multisystem disorder linking metabolic dysfunction with cardiovascular complications. While the Chinese Visceral Adiposity Index (CVAI) and Frailty Index (FI) independently predict adverse outcomes, their combined utility for stroke prediction across CKM syndrome stages 0–3 remains unexplored.

Methods: We analyzed 6,772 participants aged ≥45 years from the China Health and Retirement Longitudinal Study (2011–2020). Participants were classified into CKM stages 0–3, excluding stage 4 or baseline stroke. CVAI was calculated using age, BMI, waist circumference, triglycerides, and HDL-C. FI incorporated 32 health deficits following standardized methodology. The CVAI-FI index was derived as the product of CVAI and FI. Cumulative exposure was assessed in 4,170 participants with measurements from Waves 1 (2011) and 3 (2015). Multivariable logistic regression evaluated associations with incident stroke, adjusting for sociodemographic, behavioral, and clinical confounders. Model performance was assessed using ROC curves, with incremental value determined through NRI and IDI. Restricted cubic splines characterized dose-response relationships.

Results: During follow-up, 447 participants (6.6%) developed stroke. CVAI-FI demonstrated a significant dose-response association with stroke risk (P for nonlinearity <0.001). Each one-SD increment in CVAI-FI corresponded to 31% higher stroke risk (OR 1.31, 95% CI 1.20–1.43). Cumulative CVAI-FI achieved superior discrimination (AUC 0.675) compared to standalone CVAI (0.616), FI (0.609), and baseline CVAI-FI (0.641, all P < 0.001), with significant IDI (0.018–0.020) and NRI (0.032) improvements. Associations remained robust across subgroups, with stronger effects among individuals with secondary education or above (OR 1.83) and those without hypertension (OR 1.51).

Conclusions: The CVAI-FI index provides enhanced stroke risk stratification across CKM syndrome stages 0–3, with quantifiable improvements in discrimination and reclassification. Cumulative exposure assessment further strengthens predictive accuracy. These findings support CVAI-FI’s clinical utility for identifying high-risk individuals requiring intensified preventive interventions within emerging CKM syndrome frameworks.