Male Sex and Distal Aortic Expansion after TEVAR: A Single-Center Analysis with Bayesian Evidence Synthesis

A prior meta-analysis identified male sex as a predictor of distal aortic expansion after thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (pooled risk ratio [RR] 3.00; 95% confidence interval [CI] 1.22-7.35). This study aimed to evaluate the association between sex and distal aortic expansion in a single-center patient-level cohort and to explore the integration of prior evidence using Bayesian methods.

We retrospectively analyzed 145 consecutive patients who underwent TEVAR for type B aortic dissection or intramural hematoma between 2014 and 2023. Distal aortic expansion was defined as an increase ≥5 mm in maximal thoracic aortic diameter during follow-up. Firth logistic regression assessed the association between male sex and expansion, adjusting for preoperative aortic diameter and hypertension. Bayesian logistic regression was performed using weakly informative priors and a secondary exploratory informative prior derived from the published meta-analysis, with consideration of differences between RR and odds ratio (OR), to obtain posterior probabilities of clinically relevant effect thresholds.

Twenty-six patients (17.9%) developed expansion. Firth regression yielded an adjusted OR of 3.92 (95% CI 0.94-36.29; P = 0.064). Under a weakly informative prior, the posterior distribution remained centered near the maximum likelihood estimate with wide credible intervals, reflecting substantial uncertainty. Bayesian analysis (informative prior: log OR ∼ no+rmal [1.10, 0.46]) produced a posterior median OR of 3.43 (95% credible interval 1.58-7.85). The posterior probability that the true OR exceeds 1 was 99.8%, and that it exceeds 2 was 90.4%. Results were similar under weakly informative priors; the posterior distribution remained centered near the maximum likelihood estimate, indicating consistency with the observed data while reducing imprecision.

In this single-center cohort, male sex showed a directionally consistent association with distal aortic expansion compared with prior meta-analytic findings, although the precision of the estimate was limited by sample composition. Despite limited frequentist precision, Bayesian analysis provides a probabilistic interpretation of the effect size and demonstrates how incorporation of prior evidence may influence inference in small-sample settings. These findings should be interpreted with caution and warrant confirmation in larger, independent cohorts.