Preoperative Risk Score for Mortality Within Three Years of Non-Emergent TEVAR for Descending Thoracic Aortic Aneurysm.

Abstract

Objective: The purpose of this study is to create a validated risk score for mortality within three years of elective endovascular repair of descending thoracic aortic aneurysm (TEVAR) based on variables existing at the time of preoperative clinical presentation.

Methods: The Vascular Quality Initiative was queried for non-emergent TEVAR for degenerative, non-dissection related descending thoracic aortic aneurysms limited to aortic landing zones 2 to 5. Inclusion criteria was met by 3750 patients. Patients were divided randomly into a 70% testing cohort for risk score model creation and a 30% internal validation cohort to verify the function of the risk score. Binary logistic regression 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 .25 were assigned 0 points, and then a point was added for each rise in beta-coefficient at .25 intervals.

Results: Significant (P<.05) multivariable association with three-year mortality was noted for : advancing age decade (P<.001); nursing home status (aOR 2.63, P=.029); BMI <20 kg/m² (aOR 1.74, P=.008); active smoking status (aOR 1.44, P=.023); 6-6.9 cm TAA diameter (aOR 1.40, P=.015 relative to <6cm); 7 + cm TAA diameter (aOR 1.97, P<.001 relative to <6cm); COPD on medication (aOR 1.42, P=.029); COPD on oxygen (aOR 2.29, P<.001); renal insufficiency (aOR 1.72, P<.001); anemia (aOR 1.74, P=.001); and lack of statin medication preoperatively (aOR 1.54, P=.001). There is noted to be significantly upsloping mortality with statistically significant escalation between each risk score bundle. Patients with risk scores less than 3 experienced three-year mortality at just a 2.3% rate whereas patients with risk scores of 13 and higher had a mean 32.8% mortality at three years (OR 21.1, P<.001). There was outstanding agreement between the testing and validation groups at all risk score bundles with near identical mortality rates and no statistically significant difference at each level. AUC analysis revealed 0.7 and 0.67 for the testing and validation cohorts respectively. Hosmer-Lemeshow goodness of fit for the source testing regression was 88.2% overall accuracy and for the validation cohort regression was 87.7%.

Conclusions: A risk score for three-year mortality following TEVAR for non-dissection related descending thoracic aortic aneurysm has been created which has both good accuracy and outstanding internal VQI validation. The most impactful deleterious variables towards survival included advancing age, COPD, aneurysm diameter, anemia, renal insufficiency, tobacco use, lack of statin therapy and nursing home status.