Perioperative Kidney Function Assessment

Surgical procedures performed at eight academic and private centers nationally between July 1, 2008, and December 1, 2015 (appendix 2), were reviewed. Institutions and dates chosen were based upon availability of complete data as relevant to this study. Adult (at least 18 yr old) patients with a creatinine level collected within 30 days before surgery were included. A baseline creatinine level was defined as the preoperative serum creatinine level collected closest to the start of surgery. Cases with extremely low baseline risk (outpatient and nonoperative procedures), unique operative physiology (liver transplantation, cardiac surgery), and urologic surgeries directly affecting renal function were excluded (fig. 1). Patients without a postoperative creatinine within 7 days, as well as patients with chronic kidney disease stage 5 (preoperative estimated glomerular filtration rate less than 15 ml · min⁻¹ · 1.73 m⁻²), were excluded from primary analysis. The Chronic Kidney Disease Epidemiology Collaboration creatinine equation was used for estimated glomerular filtration rate calculation.^{27 (link)}