Joint association of body mass index and periaortic adipose tissue with type B aortic dissection: a multicenter retrospective case–control study

Type B aortic dissection (TBAD) represents a life-threatening condition with an increasing incidence. Although elevated body mass index (BMI) is associated with both TBAD incidence and mortality, the underlying mechanisms remain unclear. Periaortic adipose tissue (PAAT) increases with BMI, and the PAAT of AD shows marked inflammatory infiltration, suggesting PAAT-driven inflammation may contribute to the development of AD. However, no direct evidence links BMI and PAAT to AD. To further elucidate the obesity-inflammation-AD relationship, we aim to quantify the contributions of BMI, PAAT, and their derived indices to the risk of TBAD. This retrospective multicenter study (June-November 2025) quantified PAAT from the descending thoracic aorta distal to the left subclavian artery to the aortic bifurcation with CT angiography (CTA). Missing data were handled using Multivariate Imputation by Chained Equations (MICE). Logistic regression analyses were performed to identify TBAD risk factors. Based on the Boruta algorithm and ROC curve analysis, the variable importance for TBAD risk was assessed. Bootstrap resampling was employed for internal validation. The dose–response relationship between BMI–Volume-derived metric (BMV) and TBAD risk was further characterized by quartile stratification and restricted cubic spline (RCS). This study enrolled 376 consecutive participants. After adjusting for potential confounders, male, smoking, diabetes mellitus (DM), TC/HDLC, ApoE, PAAT area(Area), PAAT volume/length of aortic centerline (V/L), PAAT fat attenuation index (FAI), and BMV were identified as independent predictors of AD. FAI was the strongest TBAD predictor with the highest Z-score. Compared to TC/HDLC (AUC 0.572, 95% CI 0.511–0.633), ApoE (AUC 0.630, 95% CI 0.575–0.687), Area (AUC 0.657, 95% CI 0.602–0.712), FAI (AUC 0.586, 95% CI 0.528–0.643), BMI (AUC 0.627, 95% CI 0.571–0.684), BMV showed superior discriminatory performance ( P < 0.05). The internal validation showed an AUC of 0.917 (95% CI: 0.887–0.944). The Hosmer-Lemeshow test indicated good model fit ( P = 0.185), and the decision curve analysis (DCA) suggested that the model provides substantial clinical net benefit across a wide range of threshold probabilities. RCS showed an approximately linear positive association between BMV and TBAD risk (P-overall < 0.001, P-non-linear = 0.09). In this retrospective multicenter study, the BMV index, a composite measure integrating systemic and local adipose tissue factors, showed a statistical association with TBAD risk, pending validation in external cohorts.