Preoperative Risk Score for Mortality Within 3 Years of Visceral Segment Fenestrated Endovascular Aortic Repair

Objective The purpose of this study was to create a risk score for the event of mortality within three years of complex fenestrated visceral segment endovascular aortic repair utilizing variables existing at the time of preoperative presentation. Methods After exclusions, 1916 patients were identified in the Vascular Quality Initiative who were included in analysis. The first step in development of the risk score was univariable analysis for the primary outcome of mortality within three years of surgery. Chi-squared analysis was performed for categorical variables and comparison of means with independent student t-test was performed for ordinal variables. Variables which achieved a univariable P-value less than 0.1 were then placed into Cox Regression multivariable time dependent analysis for the development of mortality within three years. Variables which achieved a multivariable significance of less than 0.1 were utilized for the risk score with point weighting based on the beta-coefficient. Variables with a beta-coefficient of 0.25-0.49 were assigned one point, 0.5-0.74 two points, 0.75-0.99 three points, and 1.0-1.25 four points. A cumulative score for each patient was then summed and the percentage of patients at each score experiencing mortality within three weeks was then calculated and comparison of score outcomes was conducted with binary logistic regression. AUC analysis was performed. Results The primary outcome of mortality within three years of surgery occurred in 12.8% (245/1916) of patients. Mean age for the study population was 73.35 years (SD 8.26). Mean maximal AAA diameter was 60.43 mm (SD 10.52 mm). Mean number of visceral vessels stented was 3.3 (SD .76).Variables present at the time of surgery which were included in the risk score were : hemodialysis (3 points); age >87, COPD, hypertension, AAA diameter >77mm (all 2 points); and BMI <20 kg/m2, female sex, CHF, active smoking, chronic renal insufficiency, age 80-87, and AAA diameter 67-77 mm (all 1 point). BMI >30 kg/m2 (Mean 34.46 and Age <67 were protective (-1 point). Testing the model resulted in an AUC of .706. Hosmer and Lemeshow goodness of fit test for logistic regression utilizing the 15 different risk score total groups revealed a model predictive accuracy of 87.3%. Significant escalations in 3-year mortality were noted to occur at scores of 6 and greater. Mean AAA diameter was significantly larger for patients who had higher risk scores (P<.001). Conclusions A novel risk score for mortality within three years of fenestrated visceral segment aortic endograft has been developed which has excellent accuracy in predicting which patients will survive and derive the strongest benefit from intervention. This facilitates risk-benefit analysis and counseling of patients and families with realistic long-term expectations. This potentially enhances patient centered decision making.