Combined plasma syndecan-1 and renal resistive index as early predictors of sepsis-associated Acute kidney injury: a prospective observational study

The interplay between macro-microcirculatory dysfunction and sepsis associated acute kidney injury (SA-AKI) remains elusive. This study aimed to explore the association between hemodynamics and endothelial damage in SA-AKI by evaluating the combined predictive value of renal resistive index (RRI) and plasma syndecan-1. This prospective observational study enrolled 80 septic patients admitted to the general intensive care unit (ICU) of a tertiary hospital from May to December 2024. Plasma syndecan-1 levels were measured at admission, and RRI was assessed within 24 h of ICU admission. Univariate and multivariate logistic regression models were applied to identify independent risk factors of SA-AKI. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis by calculating the area under the curve (AUC). Among 80 septic patients, 41(51.25%) developed AKI. Syndecan-1 levels were significantly higher in the AKI group [109.95 (73.67-221.40) vs.73.67 (54.59-109.95) ng/mL, <i>p</i> = 0.007], and RRI values were markedly elevated (0.69 ± 0.08 vs. 0.60 ± 0.06, <i>p</i> < 0.001) compared to non-AKI patients. Univariate analysis revealed 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 confounders, both plasma syndecan-1 (OR = 3.57, 95%CI 1.01-12.64, <i>p</i> = 0.048) and RRI (OR = 1.19, 95% CI 1.07-1.33, <i>p</i> = 0.002) retained significance. A predictive model using a combination of plasma syndecan-1 and RRI achieved superior diagnostic performance (AUC 0.859, sensitivity 87.8%, specificity 92.3%). In patients with SA-AKI, elevated plasma syndecan-1 and RRI were identified as independent risk factors. The combination of syndecan-1 and RRI can serve as synergistic biomarkers for the prediction of SA-AKI.