Albuminuria as a Key Factor Associated with Ambulatory Arterial Stiffness: A Hierarchical Multivariable Analysis

<b>Background:</b> The ambulatory arterial stiffness index (AASI) is a non-invasive surrogate marker of arterial stiffness; however, the relative contributions of hemodynamic, cardiometabolic, and renal factors to the AASI remain incompletely understood. This study aimed to identify the independent clinical factors associated with the AASI. <b>Methods:</b> This retrospective cross-sectional study included 290 individuals aged 18-65 years who underwent ABPM between 2020 and 2024. Participants were classified as hypertensive or normotensive based on ABPM criteria. Hemodynamic parameters, cardiometabolic indices, and renal biomarkers, including the urine albumin-to-creatinine ratio (uACR), were assessed. <b>Results:</b> Associations between the AASI and clinical variables were evaluated using the following correlation analyses and hierarchical multivariable linear regression models: Model 1-1b (hemodynamic), Model 2 (hemodynamic plus cardiometabolic) and Model 3 (hemodynamic plus cardiometabolic plus renal). The AASI was significantly higher in hypertensive individuals compared with normotensive controls. In correlation analyses, the AASI was positively associated with age, systolic blood pressure parameters, atherogenic lipid indices, and uACR and negatively associated with diastolic blood pressure parameters and the estimated glomerular filtration rate (eGFR). In multivariable regression analyses, age, maximum systolic blood pressure, and maximum diastolic blood pressure remained independently associated with the AASI across models. uACR was also independently associated with the AASI in the fully adjusted model. <b>Conclusions:</b> The AASI is primarily associated with hemodynamic load and age-related vascular changes. Among non-hemodynamic factors, albuminuria demonstrated the strongest association with the AASI after multivariable adjustment. These findings suggest the potential clinical value of the AASI as a practical marker for early cardiorenal risk assessment using routine ABPM data.