The Moderating Effect of Urinary Protein Status on the Association Between Visceral Adiposity Index and Retinal Microvascular Parameters

Background: isceral fat accumulation is a well-established risk factor for both cardiovascular and microvascular diseases. The lipid accumulation product (LAP), visceral adiposity index (VAI), and Chinese visceral adiposity index (CVAI) are recognized tools for assessing visceral obesity. Retinal microvascular parameters serve as non-invasive biomarkers of systemic microvascular health, while urinary protein is a marker of early renal injury and endothelial dysfunction. Currently, evidence linking visceral obesity indices to retinal microvasculature is limited, and whether urinary protein status modifies this association remains unclear. This study aimed to investigate the associations of LAP, VAI, and CVAI with retinal microvascular parameters and to examine the potential moderating effect of urinary protein status on these associations, thereby identifying specific subgroups at elevated risk for microvascular damage. Methods： This study included 3,401 healthy individuals undergoing physical examinations. Participants were categorized into a positive group (n=1,008) and a negative group (n=2,393) based on their urine protein results. Demographic data, metabolic indicators, and retinal vascular parameters were collected. Spearman/Pearson correlation analysis was employed to explore the associations among these indicators. Multivariate linear regression analysis stratified by urine protein status was conducted to verify the independent association between the visceral obesity index and AVR, as well as the differences between the groups. Results： Baseline characteristics revealed significantly higher levels of triglycerides (TG), LAP, and VAI in the urinary protein-positive group (all P < 0.01). Overall correlation analysis demonstrated that LAP, VAI, and CVAI were all inversely correlated with AVR (all P < 0.001). Stratified analysis indicated that in the protein-positive group, the negative correlations of CRAE with TG, LAP, and VAI were substantially stronger or showed a reversed pattern. While AVR was negatively associated with all adiposity indices in both groups, the associations were more pronounced in the positive group. Multiple linear regression analysis, after adjustment for age and sex, showed that LAP, VAI, and CVAI exerted stronger negative predictive effects on AVR and contributed more to the model's explanatory power in the positive group (ΔR²: 0.007–0.009) compared to the negative group (ΔR²: 0.002–0.005). Conclusions: Visceral adiposity indices are independently associated with retinal microvascular narrowing, and this association is significantly enhanced in individuals with positive urinary protein.