The Society for Vascular Surgery Vascular Quality Initiative underestimates the risk associated with mild postoperative acute kidney injury.

Abstract

Recently the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) lowered the thresholds for acute kidney injury (AKI) to align with the Kidney Disease: Improving Global Outcomes (KDIGO) definition (≥0.3 mg/dL change from the reference serum creatinine [sCr] within 48 hours of surgery or initiation of dialysis). The Vascular Quality Initiative (VQI) defines postoperative renal dysfunction as a rise in sCr >0.5 mg/dL from baseline or new postoperative temporary or permanent dialysis throughout the postoperative course. This definition does not align with guidelines outside of VQI and may not capture subtle changes in perioperative renal function that can impact patient outcomes. This was a single-institution retrospective review of adult patients with no previous history of preoperative hemodialysis undergoing elective or nonelective major vascular surgery that were registered with the VQI. Patients undergoing endovascular abdominal or thoracic aortic repair, open abdominal aortic aneurysm repair, and suprainguinal or infrainguinal bypasses were included. A total of 932 patients were included. AKI occurred in 6% of patients using the VQI definition (VQI-AKI), as compared with 18% of patients using a modified KDIGO definition (≥0.3 mg/dL change from the reference sCr within 48 hours of surgery or initiation of dialysis [mKDIGO-AKI]). Regardless of the definition used, patients with AKI had longer postoperative length of stay and higher morbidity and mortality. One-year survival was lower for VQI-AKI patients vs mKDIGO-AKI patients, 57% vs 77%, respectively (log-rank P < .001). In a multivariable Cox regression model adjusting for age, nonelective admission status, and history of congestive heart failure, patients with mKDIGO-AKI had 2.5× higher odds of postoperative mortality compared with patients without AKI. The current VQI definition underestimates the rate of clinically significant AKI when compared with mKDIGO, as patients with newly identified AKI using the mKDIGO definition are associated with increased postoperative complications and decreased survival as compared with those without AKI. Given the importance of AKI on short- and long-term outcomes, the inclusion of preoperative and highest postoperative sCr within 7 days of surgery among patients at high risk for postoperative AKI (open abdominal aortic aneurysm, supra/infrainguinal bypass, thoracic endovascular aortic repair, and endovascular aortic repair) may be warranted to facilitate appropriate benchmarking and quality improvement efforts.