Association of the Systemic Immune-Inflammation Index with Ascending Aortic Diameter and Dilatation: A Retrospective Cross-Sectional Study

Background and Objectives: Complete blood count-derived inflammatory indices are inexpensive and widely available, but data on their relationship with ascending aortic size are limited. This study examined the association between the systemic immune-inflammation index (SII) and ascending aortic diameter, and compared these indices according to the presence of ascending aortic dilatation (AAD) defined by a 40 mm threshold. Materials and Methods: In this single-centre retrospective cross-sectional study, 251 patients aged 18 years or older (mean age, 53.1 ± 16.7 years; range, 18–95 years; 160 men) who underwent thoracic computed tomography angiography were grouped by maximum tubular ascending aortic diameter (<40 mm, n = 158; ≥40 mm, n = 93). Inference for the primary linear model was based on heteroscedasticity-consistent (HC3) standard errors. Height and weight were not recorded, so the models could not be adjusted for body size.