Cohort study of risk factors for 30-day readmission after abdominal aortic aneurysm repair.

Background: We conducted a retrospective cohort study of thirty-day readmission after abdominal aortic aneurysm (AAA) repair. Patients and methods: Inpatients (2009-2016) undergoing elective AAA repair were selected from the multicenter Cerner Health Facts® database using ICD-9 procedure codes. We identified characteristics associated with 30-day readmission with chi-square analysis and logistic regression. Results: 4,723 patients undergoing elective AAA procedures were identified; 3,101 endovascular aneurysm repairs (EVAR) and 1,622 open procedures. Readmission differed by procedure type (6.5 % EVAR vs. 9.3 % open, p =.0005). Multivariable logistic regression found that patients undergoing EVAR were less likely to be readmitted (OR 0.71, 95 % CI 0.54-0.92) than patients undergoing open repair. The following risk factors were associated with 30-day readmission following any AAA repair: surgical site infection during the index admission (OR 2.79, 95 % CI 1.25-6.22), age (OR 1.03, 95 % CI 1.01-1.05), receipt of bronchodilators (OR 1.34, 95 % CI 1.06-1.70) or steroids (OR 1.45, 95 % CI 1.04-2.02), serum potassium > 5.2 mEq/L (OR 1.89, 95 % CI 1.16-3.06), and higher Charlson co-morbidity scores (OR 1.12, 95 % CI 1.04-1.21). Subgroup analysis revealed that age (OR 1.02, 95 % CI 1.01-1.04), higher Charlson comorbidity scores (OR 1.20, 95 % CI 1.09-1.33), and receipt of post-operative bronchodilators (OR 1.39, 95 % CI 1.03-1.88) were risk factors for 30-day readmission following EVAR. After open procedures, readmission was associated with surgical site infection during the index admission (OR 2.91, 95 % CI 1.17-7.28), chronic heart failure (OR 2.18, 95 % CI 1.22-3.89), and receipt of post-operative steroids (OR 1.92, 95 % CI 1.24-2.96). The most common infections were pneumonia after open procedures and urinary tract infection after EVAR. Conclusions: The risk factor most associated with 30-day readmission after elective AAA repair was surgical site infection. Awareness of these risk factors and vulnerable groups may help identify high-risk patients who could benefit from increased surveillance programs to reduce readmission.