O63: POST-OPERATIVE ACUTE KIDNEY INJURY IN PATIENTS UNDERGOING MAJOR GASTROINTESTINAL SURGERY— AN OBSERVATIONAL COHORT STUDY AND EXTERNAL VALIDATION OF A PROGNOSTIC MODEL

Acute kidney injury (AKI) is well-recognised as a significant cause of morbidity and mortality. Due to limited evidence on the longer-term implications, this study aimed to explore the association of postoperative AKI one-year survival and renal function in patients undergoing major gastrointestinal and liver surgery. Method Patients undergoing major gastrointestinal surgery in the prospective Outcomes of Kidney Injury after Surgery (OAKS) study across UK and Ireland were followed up at one-year postoperatively. The primary outcome was survival at 1-year and secondary outcomes included the composite “Major Adverse Kidney Events” outcome at day 365 (MAKE-365), with respective multivariable Cox-regression and logistic regression analysis performed. Result Of 62.2% of OAKS patients (n=3,575/5,745) with 1-year follow-up, there were no significant differences compared to those without follow-up. Among the follow-up cohort, 8.0% (n=269) patients died. On univariate analysis, patients experiencing 7-day postoperative AKI had a significantly higher hazard of death between 30 to 365 days postoperatively (HR: 2.10, 95% CI: 1.50-2.94, p<0.001) compared to patients who did not. This persisted on multivariable Cox-regression (HR: 1.67, 95% CI: 1.17-2.40, p=0.005). Furthermore, 9.1% (n=305) patients met the MAKE-365 endpoint. Multilevel logistic regression analysis demonstrated that the MAKE-365 endpoint was independently associated with both stage 1 (OR: 1.78, 95% CI: 1.22-2.61, p=0.003) and stage 2-3 7-day postoperative AKI (OR: 6.13, 95% CI: 3.97-9.45, p<0.001). Conclusion Post-operative AKI is associated with significantly higher rate of 1-year mortality and MAKE-365 endpoints. Improved monitoring of these patients may be warranted to identify and facilitate potential avenues for intervention Take-home message Post-operative AKI is associated with significantly higher rate of 1-year mortality. Hence, early detection and improved monitoring of patients with AKI with improve long-term outcomes of these patients.