Preoperative risk score for mortality within 3 years of visceral segment fenestrated endovascular aortic repair

Abstract

Objective: The purpose of this study was to create a risk score for the event of mortality within 3 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 the analysis. The first step in development of the risk score was univariable analysis for the primary outcome of mortality within 3 years of surgery. χ² analysis was performed for categorical variables, and comparison of means with independent Student t-test was performed for ordinal variables. Variables that 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 3 years. Variables that 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 to 0.49 were assigned 1 point, 0.5 to 0.74 2 points, 0.75 to 0.99 3 points, and 1.0 to 1.25 4 points. A cumulative score for each patient was then summed, the percentage of patients at each score experiencing mortality within 3 weeks was then calculated, and a comparison of score outcomes was conducted with binary logistic regression. Area under the curve analysis was performed.

Results: The primary outcome of mortality within 3 years of surgery occurred in 12.8% of patients (245/1916). The mean age for the study population was 73.35 years (standard deviation [SD], 8.26 years). The mean maximal abdominal aortic aneurysm (AAA) diameter was 60.43 mm (SD, 10.52 mm). The mean number of visceral vessels stented was 3.3 (SD, 0.76). Variables present at the time of surgery that were included in the risk score were: hemodialysis (3 points); age >87, chronic obstructive pulmonary disease, hypertension, AAA diameter >77 mm (all 2 points); and body mass index <20 kg/m², female sex, congestive heart failure, active smoking, chronic renal insufficiency, age 80 to 87 years, and AAA diameter 67 to 77 mm (all 1 point). BMI >30 kg/m² (mean, 34.46 kg/m²) and age <67 years were protective (-1 point). Testing the model resulted in an area under the curve of 0.706. 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 3 years of fenestrated visceral segment aortic endograft has been developed that 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.

Keywords: Mid term survival; Visceral segment endovascular aortic repair.