Predicting 1-year mortality after elective abdominal aortic aneurysm repair

Abstract

Benefit of prophylactic abdominal aortic aneurysm (AAA) repair requires sufficient survival to overcome operative risk. Since death within 1 year of elective open or endovascular (EVAR) infrarenal AAA repair likely indicates ineffective treatment, we developed a prediction model for 1-year mortality to aid clinical decision-making. We used a prospective registry of 1387 consecutive patients who had undergone elective AAA repair from 2003 to 2007 by 50 surgeons from 11 hospitals in Northern New England. Cox proportional hazards were used to analyze potential risk factors for 1-year mortality, including medical comorbidities, aortic clamp site, preoperative risk factor modification (eg, beta-blockade), and aneurysm diameter. Thirty-day and 1-year mortality after open repair (n = 748) was 2.3% and 5.8%, and after EVAR (n = 639) was 0.5% and 5.7%, respectively. Factors associated with death within 1-year after open repair were: age >/= 70 (P = .007; hazard ratio [HR] 2.9, 95% confidence interval [CI] 1.3-6.3), history of chronic obstructive pulmonary disease (COPD) (P < .0001; HR 3.6, 95% CI 1.9-7.0), chronic renal insufficiency (creatinine >/= 1.8) (P = .008; HR 2.8, 95% CI 1.3-6.2) and suprarenal aortic clamp site (P < .0001; HR 3.8, 95% CI 1.9-7.5). Depending on the number of risk factors present, predicted 1-year mortality after open repair varied from 1% in patients with no risk factors to 67% in patients with four risk factors. Our model demonstrated excellent correlation between observed and expected deaths (r = 0.97). For EVAR, identified risk factors for death within 1 year included a history of congestive heart failure (CHF) (P = .002; HR 3.2, 95% CI 1.6-6.5), and aneurysm diameter >/=6.5 cm (P = .04 95% CI 1.0-4.8). Depending on the number of risk factors present, predicted mortality ranged from 3.6% to 23%. A model using CHF and aneurysm diameter correlated well with actual mortality rates, with an observed to expected ratio of 0.96. Predictors of 1-year mortality can identify patients less likely to benefit from elective AAA repair. These factors differ for open repair vs EVAR and should be considered in individual patient decision-making. Our EVAR model had less impact on 1-year survival, even if CHF and large AAA diameter were present. However, a combination of age, COPD, renal insufficiency, and need for suprarenal clamping have significant impact on 1-year mortality after open AAA repair. Consideration of these variables should assist decision-making for elective AAA repair, especially in borderline cases.