Preoperative Statins and Acute Kidney Injury After Cardiac Surgery: Utilization of a Consensus Definition of Acute Kidney Injury

BACKGROUND: Previous trials investigating preoperative statin use for prevention of acute kidney injury following cardiovascular surgery were limited to patients undergoing a specific procedure and many used nonconsensus definitions of acute kidney injury. OBJECTIVE: To use a consensus definition of acute kidney injury for evaluating the association of preoperative statin use with the development of acute kidney injury following cardiac surgery utilizing cardiopulmonary bypass. METHODS: We retrospectively evaluated a cohort of 667 patients >= 18 years who underwent any cardiac surgery on cardiopulmonary bypass between April 2007 and I May 2009 at Mercy Hospital in Scranton, PA. Patients were excluded if they were receiving preoperative renal replacement therapy, had stage 5 chronic kidney disease, or did not have a postoperative serum creatinine level assessed. The primary outcome was the odds of developing acute kidney injury given the use of preoperative statins. Acute kidney injury was defined based on the Acute Kidney Injury Network criteria as either an absolute increase in serum creatinine of >= 0.3 mg/dL or 1.5 times baseline, or the need for postoperative renal replacement therapy. RESULTS: The final analysis included 563 patients; 356 were receiving preoperative statins. The incidence of acute kidney injury was 35.1% in the statin group and 26.1% in the non-statin group. On univariate analysis statins were associated with an increase in the odds of acute kidney injury (OR 1.53; 95% CI 1.05 to 2.24). Multivariate logistic regression did not demonstrate an association of statins with acute kidney injury (OR 1.36; 95% CI 0.904 to 2.05). Repeating the analysis using 312 propensity score matched patients also showed no association of statins with acute kidney injury (OR 1.17; 95% CI 0.715 to 1.93). CONCLUSIONS: Our findings do not support the hypothesis that preoperative statin use is associated with a decrease in the incidence of acute kidney injury following cardiac surgery utilizing cardiopulmonary bypass.