Acute kidney injury post‐major orthopaedic surgery: A single‐Centre case–control study

Aim To identify risk factors for acute kidney injury following major orthopaedic surgery. Methods We included all patients undergoing major orthopaedic surgery at University Hospital Geelong between 2008 and 2014 in the study. Out of 2188 surgeries audited, we identified cases of acute kidney injury using the RIFLE criteria and matched those to controls 2:1 for age, sex, procedure and chronic kidney disease stage. We reviewed their records for risk factors of postoperative acute kidney injury, including medications such as gentamicin, diuretics, non‐steroidal anti‐inflammatory drugs and angiotensin‐converting enzyme inhibitor or angiotensin receptor blocker use. We reviewed the patients' history of cardiovascular disease, chronic liver disease, hypertension and diabetes mellitus along with presence of sepsis and obesity. Associations of hypothetical risk factors were estimated using conditional logistic regression. Results We identified 164 cases of AKI in an elderly cohort (median age = 73 years). Controlling for baseline comorbidities, both diuretic and angiotensin‐converting enzyme inhibitor or angiotensin receptor blocker use were found to be associated with a twofold risk of acute kidney injury (diuretic – OR 2.06 95% CI:1.30–3.26, P  < 0.005, angiotensin‐converting enzyme inhibitor or angiotensin receptor blocker use OR 2.09 95% CI:1.31–3.32, P  < 0.005). A dose‐effect model accounting for perioperative nonsteroidal anti‐inflammatory drug administration demonstrated a linear relationship between the number of times these drugs were given and postoperative acute kidney injury risk (OR 1.35 95% CI:1.05–1.73, P  = 0.02). Conclusions We identified perioperative diuretics, non‐steroidal anti‐inflammatory drugs and angiotensin‐converting enzyme inhibitor or angiotensin receptor blocker to be significantly associated with postoperative AKI. Further prospective studies are required to confirm this.