Risk factors and long-term outcomes of elderly patients complicating with acute kidney injury after type A acute aortic dissection surgery: a retrospective study

Background: To identify risk factors and long-term outcomes for acute kidney injury (AKI) in elderly patients who underwent type A acute aortic dissection (TA-AAD) emergency surgeries. Methods: This retrospective study enrolled 214 consecutive patients who underwent TA-AAD emergency surgeries between January 2014 to December 2018 in Nanjing Drum Tower hospital. The diagnosis of AKI was made based on the Kidney Disease: Improving Global Outcomes definition (KDIGO) criteria. Multivariable regression analysis was performed to identify risk factors for postoperative AKI. Kaplan-Meier curves were generated to compare the long-term outcomes between patients with and without AKI complication after TA-AAD surgeries. Results: Among all enrolled patients, 114 (53.3%) developed AKI during postoperative period. The median age of patients with or without AKI was 68.0 (64.0, 74.0) and 66.0 (62.0, 72.8) years respectively. Renal replacement therapy (RRT) was required in 43 patients (20.1%). The 30-day mortality rate was 21.5% in all enrolled patients with 26.3% in AKI group and 16.0% in non-AKI group (P=0.067) respectively. Longer mechanical ventilation duration was identified as the only independent risk factor for developing AKI by multivariable logistic regression analysis. In addition, our data suggested that the long-term cumulative survival rate was different between two groups. Conclusions: Postoperative AKI after TA-AAD surgeries was common and associated with worsened long-term mortality in elderly patients. Longer postoperative mechanical ventilation duration was identified as the only independent risk factor for the development of AKI.