Abdominal aortic aneurysm (AAA) is defined by a progressive localized medial extracellular matrix remodeling, segmental dilation, and aortic rupture with mortality risk exceeding 30%. Inflammation is strongly linked to medial matrix changes in AAA, including positive correlations with C-reactive protein (CRP) and serum amyloid A (SAA). The goal of this study was to evaluate the longitudinal association between plasma CRP or SAA levels and aortic diameter during 30 months of follow-up after initial blood collection. Subjects were participants in a randomized drug trial with centrally read computerized tomography scans and plasma evaluation every 6 months. Using generalized linear models adjusted for baseline aortic diameter, treatment assignment, age, sex, diabetes status, statin use, and smoking status, we examined predictive relationships in 113 participants. CRP at baseline demonstrated significant associations with aortic diameter beginning at 12 months and persisting through 30 months. Effect sizes increased over time, with beta coefficients ranging from 0.002 (p = 0.021) at 12 months to 0.108 (p = 0.008) at 30 months. The strongest associations were observed at 18 months (p = 0.0006) and 30 months, suggesting CRP may be a marker of accelerated aortic remodeling. Model fit comparisons indicated that raw CRP values consistently outperformed log-transformed CRP, except marginally at 30 months, supporting the use of untransformed CRP in predictive modeling. In contrast, SAA showed no significant association with MTD at any subsequent time point, indicating limited utility as a predictor in this context. Further analyses incorporating CRP and SAA measured at later intervals (12 months) confirmed these findings, with CRP maintaining a modest association at 18 months while SAA remained non-predictive. Exploratory evaluation of CRP/SAA ratios yielded no meaningful associations. Overall, CRP emerges as a more reliable biomarker for long-term changes in diameter compared to SAA, highlighting a potential role in monitoring disease progression. Further exploration of the unique aspects of CRP as a marker of inflammation compared to SAA may provide novel insights into the pathology of the inflammatory process. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Farahat et al. (Fri,) studied this question.