Association of blood urea nitrogen to albumin ratio with cerebral small vessel disease and its ischemic imaging markers: a cross-sectional study

Background This study aims to assess the association between blood urea nitrogen to albumin ratio (BAR) and cerebral small vessel disease (CSVD) and its common ischemic neuroimaging markers, including white matter hyperintensities (WMH), enlarged perivascular spaces (EPVS), and lacunes. Methods This cross-sectional study involved 762 participants, including 452 patients with CSVD and 310 non-CSVD controls. Their clinical data, hematological markers, and neuroimaging results were collected. The relationship between the BAR index and CSVD/ischemic neuroimaging markers was assessed using Spearman’s rank correlation coefficient, multivariable logistic regression, and restricted cubic splines. Subgroup analyses were performed stratified by various covariates. Model performance and calibration were evaluated using ROC analysis, bootstrap validation, and calibration curves. Sensitivity analyses were conducted to assess the robustness of associations against varying levels of kidney function. Results After adjusting for confounding factors, BAR was positively associated with CSVD (OR: 1.77, 95% CI: 1.35–2.33, p < 0.001), WMH (OR:1.55, 95% CI: 1.22–1.96, p < 0.001), and EPVS (OR: 2.09, 95% CI: 1.71–2.57, p < 0.001). However, BAR was not related to lacunes (OR: 1.12, 95% CI: 0.92–1.36, p = 0.302). In BAR’s classification model, compared to the lowest quantile, the OR for the risk of CSVD in the middle and highest quantiles was 2.40 (95% CI: 1.68–3.43) and 4.25 (95% CI: 2.91–6.21), respectively (P for Trend < 0.001). In restricted cubic splines, after adjusting covariates, the association between BAR and CSVD (P overall < 0.001, P non-linear = 0.872) and WMH (P overall = 0.001, P non-linear = 0.145) was linear and dose-responsive, while the relationship was nonlinear with EPVS (P non-linear = 0.001). Crucially, sensitivity analyses confirmed the robustness of these associations against varying degrees of kidney function. Additionally, ROC analysis revealed that BAR was associated with CSVD (AUC: 0.701, 95% CI: 0.664–0.738). Model 4 displayed the optimal discriminative performance (AUC: 0.914, 95% CI: 0.895–0.933), which was further supported by bootstrap internal verification and excellent calibration (Brier score = 0.117). Conclusion BAR is independently associated with CSVD and its ischemic imaging markers, highlighting its potential as a novel and cost-effective biomarker. These findings warrant further investigation to determine its utility for risk stratification and its potential role in primary care screening protocols.