Risk factors and outcomes associated with acute kidney injury following ruptured abdominal aortic aneurysm

BACKGROUND: Current data describing the epidemiology of acute kidney injury (AKI) following repair of ruptured abdominal aortic aneurysm (rAAA) are limited and long-term outcomes are largely unknown. Our objectives were to describe the incidence rate, risk factors, clinical course and long-term outcomes of AKI following rAAA repair. METHODS: Retrospective population-based cohort study of all referrals undergoing emergency repair of rAAA in Northern Alberta from January 1, 2002 to December 31 2009. Demographic, clinical, physiologic and laboratory data were extracted. AKI was defined and classified according to the AKIN criteria. RESULTS: In total, 140 patients survived to receive emergent rAAA repair. Post-operative AKI occurred in 75.7% of patients (n = 106), 78.3% (n = 83) of which occurred during the initial 24 hours of ICU admission. AKIN stage 1, 2, and 3 occurred in 47 (33.6%), 36 (25.7%) and 23 (16.4%), respectively, with 19 patients receiving renal replacement therapy (RRT). Several clinical and biochemical patient factors were associated with incident AKI, including baseline estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m(2) (odds ratio [OR] 2.94; 95% CI, 1.15-7.51, p = 0.03), need for mechanical ventilation (OR 22.7; 95% CI, 7.0-72.1, p < 0.0001) and vasoactive therapy (OR 9.9; 95% CI, 3.0-32.2, p < 0.0001) and higher mean APACHE II scores (25.7 [8.2] vs. 16.3 [4.9], p < 0.0001). AKI was associated with a higher ICU (28.3% vs. 0%; p = 0.0008) and in-hospital case-fatality rate (35.9% vs. 0%, p = 0.0001). Of 102 survivors to discharge, 65.7% (n = 67) recovered to baseline kidney function. In multivariable analysis, greater severity of AKI (OR 5.01; 95% CI, 2.34-10.7, p < 0.001) and lower baseline eGFR (OR 0.96; 95% CI, 0.93-0.99, p = 0.03) were associated with non-recovery. AKI remained independently associated with 1-year mortality after adjusting for age, sex, comorbidity, and illness severity (OR 5.21; 95% CI, 1.04-26.2, p = 0.045; AUC 0.83; H-L GoF, p = 0.26). Among survivors at 1-year, only 63.4% (n = 55) had complete kidney recovery. CONCLUSIONS: Following rAAA repair, AKI is a common complication independently associated with long-term post-operative mortality. A significant proportion of AKI sufferers in this setting fail to recover to baseline kidney function.