Combined Plasma Syndecan-1 and Renal Resistive Index as Early Predictiors of Sepsis-Associated Acute Kidney Injury: a prospective observational study

Background In septic patients, the interplay between macro-microcirculatory dysfunction and acute kidney injury (AKI) remains elusive. The purpose of this study was to explore the association between hemodynamics and endothelial damage in sepsis associated AKI (SA-AKI) by evaluating the combined predictive value of renal resistive index (RRI) and plasma syndecan-1. Methods This prospective observational study enrolled 80 septic patients admitted to the general intensive care unit of (ICU) a tertiary hospital from May to December 2024. AKI was diagnosed according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Plasma syndecan-1 levels were measured at admission and RRI was assessed within 24 hours of ICU admission. Univariate and multivariate logistic regression models were applied to determine independent risk factors of SA-AKI. Predictive models were constructed to verify the effectiveness. Diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis by calculating the area under the curve (AUC). Results Among 80 septic patients, 41 (51.25%) developed AKI. Syndecan-1 levels were significantly higher in AKI group [109.95 (73.67,221.40) vs. 73.67(54.59,109.95)ng/ml, P  = 0.007], and RRI values were markedly elevated (0.69 ± 0.08 vs. 0.60 ± 0.06, P  < 0.001) compared to non-AKI patients. Univariate analysis revealed that syndecan-1 (OR = 2.68, 95%CI 1.29–5.59) and RRI (OR = 1.18, 95%CI 1.09–1.28) as predictors of AKI. In multivariate models adjusted for confounding factors, both plasma syndecan-1 (OR = 3.57, 95%CI 1.01–12.64, P  = 0.048) and RRI (OR = 1.19, 95% CI 1.07–1.33, P  = 0.002) retained statistically significant. Predictive Model using a combination of plasma syndecan-1 and RRI achieved superior diagnostic performance (AUC 0.859, sensitivity 87.8%, specificity 92.3%). Conclusions In patients with SA-AKI, elevated plasma syndecan-1 and RRI were identified as independent risk factors for SA-AKI. The combination of syndecan-1 and RRI can serve as synergistic biomarkers for prediction of SA-AKI.