A preoperative risk score for elective aorto-bifemoral artery bypass accurately predicted 3-year mortality, ranging from 2.6% for negative scores to 43.8% for scores >16 (OR 28.6, P<.001).
Cohort (n=5,912)
A newly developed preoperative risk score accurately predicts 3-year mortality following elective aortobifemoral artery bypass, which may help guide patient selection for open surgical reconstruction versus endovascular therapy.
Effect estimate: OR 28.6
Absolute Event Rate: 43.8% vs 2.6%
p-value: p=<.001
OBJECTIVE The purpose of this study was to create a risk score for mortality within three years of elective aorto-bifemoral artery bypass for aorto-iliac arterial occlusive disease based on variables at the time of preoperative clinical presentation utilizing 5912 patients in the Vascular Quality Initiative. METHODS Multivariable Cox regression time dependent analysis was performed for the outcome of three-year mortality utilizing variables which achieved a univariable P value < .05. Using this regression, it was determined which variables have a multivariable association for the outcomes as defined by a regression P value of .05 or less. A risk score was then created for the primary outcome. Variables with a multivariable P-value < .05 from the above-mentioned regression were included in the risk score and weighted based on their respective regression beta-coefficient in a point scale. Variables with a beta-coefficient of less than .2 were assigned 1 point, and then a point was added for each rise in beta-coefficient at .2 intervals. Mortality rate at each risk score bundle was then calculated for the testing and validation cohorts. Supplemental machine learning (ML) IBM SPSS modeler software analysis was conducted as well for the primary outcome RESULTS: Factors with a multivariable (P<.05) association with 3 year mortality that were ultimately included the risk score were : home in a non-metropolitan area (HR 1.44, P=.017); female sex (HR 1.25, P=.04); living in a neighborhood within the most 20% of disadvantaged on ADI (HR=1.31, P=.026); body mass index (BMI) <20 kg/m2 (HR 1.80, P<.001); age <40 (HR .247, P=.036); non-insulin dependent diabetes (HR 1.50, P=.005); CHF (HR 1.95, P=.036); end stage renal disease (ESRD) on dialysis (HR 5.36, P<.001); renal insufficiency (HR 1.45, P=.023); anemia (HR 1.84, P<.001); indication of ischemic rest pain (HR 1.6, P<.001); and need for outflow endarterectomy at distal anastomosis sites (HR 1.35, P=006). There was noted to be a steep escalation in 3-year mortality rates with each advancing risk score bundle. Patients with negative risk scores had just a 2.6% 3-year mortality, while patients with scores over 16 experienced a 43.8% three-year mortality rate (OR 28.6, P<.001). Hosmer-Lemeshow goodness of fit testing revealed 92.1% total model accuracy with a P=1.0 where a P-value of greater than .05 indicates a good model fit overall. There was no statistically significant difference in mortality rate between the testing and validation cohorts at any of the risk score bundles. SPSS modeler analysis revealed XG Boost to be the most accurate ML method with an AUC of .843 and excellent variable importance agreement with the risk score weighting. CONCLUSIONS A risk score for three-year mortality following elective aorto-bifemoral artery bypass utilizing preoperative variables has been created which has both good accuracy and outstanding internal VQI validation. The data herein has the potential to guide physicians in choosing on which patients to perform direct aortic open surgical reconstruction versus endovascular therapy or extra-anatomic bypass.
Damore et al. (2026) conducted a cohort in aorto-iliac arterial occlusive disease (n=5,912). Preoperative risk score was evaluated on 3-year mortality (OR 28.6, p=<.001). A preoperative risk score for elective aorto-bifemoral artery bypass accurately predicted 3-year mortality, ranging from 2.6% for negative scores to 43.8% for scores >16 (OR 28.6, P<.001).