Variations in the Risk of Acute Kidney Injury Across Intraabdominal Surgery Procedures

BACKGROUND: The literature on perioperative acute kidney injury (AKI) focuses mainly on cardiac and major vascular surgery. Among noncardiac general surgery procedures, intraabdominal general surgery has been identified as high risk for developing AKI, but variations in AKI risk and its impact on 30-day mortality among different types of abdominal surgeries are not well characterized. METHODS: We used the American College of Surgeons National Surgical Quality Improvement Program (2005-2010) to identify patients in 15 intraabdominal general surgery procedure categories (n = 457,656). AKI was defined as an increase in the creatinine level of >2 mg/dL above baseline and/or dialysis. Relative risk regression modeling was used to assess the relative risks of AKI across the procedures. The relationships among surgical procedure, AKI, and 30-day mortality stratified by procedure type were assessed using relative risk regression. RESULTS: The overall incidence of AKI among intraabdominal surgery patients was 1.1%, which varied from 0.2% in appendectomy and 0.3% in gastric bypass patients to 2.6% in small bowel resection and 3.5% in exploratory laparotomy patients. Of the patients who developed AKI, 31.3% died within 30 days, compared with 1.9% of those who did not develop AKI: After adjusting for comorbidities and operative factors, AKI was associated with a 3.5-fold increase in the risk of 30-day mortality (adjusted risk ratio, 3.51, 95% confidence interval [CI], 3.29-3.74). Among individual procedures, the estimated adjusted risk ratio of 30-day mortality associated with AKI ranged from 1.87 (95% CI, 1.62-2.17) in exploratory laparotomy to 31.6 (95% Cl, 17.9-55.9) in gastric bypass. CONCLUSIONS: The incidence of AKI and the impact of AKI on 30-day mortality vary markedly across procedures within intraabdominal general surgery. This highlights the importance of pre-operative risk stratification and identifies procedure type as a significant risk factor for AKI and 30-day mortality.