Volumetric Nephrogram Correlates with Long-Term Value Following Aortic Aneurysm Repair
Lauren E. Trakimas, D.O., Khurram Rasheed, M.D., Doran Mix, M.D., Jennifer L. Ellis, M.D., Roan Glocker, M.D., Adam Doyle, M.D., Kathleen Raman, M.D., Michael C. Stoner, M.D..
University of Rochester, Rochester, NY, USA.
Objective: Our prior work has demonstrated that both chronic kidney disease (CKD) and a novel metric of renal volume and perfusion, volumetric nephrogram (VN), is associated with atherosclerotic disease burden. The hypothesis of this study is that VN is an independent predictor of repair cost and of long-term survival in patients undergoing aortic aneurysm repair.
Methods: Patients who underwent intact infrarenal AAA repair over a 5-year period were analyzed. Pre-operative CTAs were reviewed using volumetric software to derive VN (Hounsfield Units*L (HU*L)). The relationship of VN to mortality was examined using receiver-operator and Kaplan-Meier curves. A multivariate analysis was used to determine correlates of 10-year survival, and value of repair (survival [days] / cost [k$]) was calculated.
Results: A total of 378 patients were identified with a mean age of 73.7 ± 0.5 years. VN < 22.5 HU*L was correlated with CKD (AUC = 0.764, p = <0.0001) and with mortality (AUC = 0.646, p = <0.0001). Survival analysis showed that VN < 22.5 HU*L was associated with mortality at 10 years (Figure, p<0.0001). Mortality was also related to chronic obstructive pulmonary disease (OR= 1.96, CI 1.08-3.53, p= 0.026) and age (OR= 2.39, CI= 1.26-4.54, p= 0.008), while statin-use was protective (OR= 0.46, CI= 0.22-0.96, p= 0.039). Patients in the high VN group demonstrated a better value of aortic repair compared to the low VN group (72.3±2.8 d/k$ versus 48.2±3.7 d/k$, p < 0.001).
Conclusions: These data are the first to demonstrate that a patient’s functional kidney mass, as measured by VN, is associated with 10-year survival following AAA repair and health care expenditure. These data confirm our hypothesis that as a measure of atherosclerotic burden, VN allows for the independent stratification and value calculation of higher-risk, lower value patients. VN is a readily available anatomical data point, which aids in the construct of value-based purchasing arrangements between hospitals and payors for aortic disease management.
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