Creatinine Elevations from Baseline at the time of Cardiac Surgery are Associated with Postoperative Complications

Abstract Objectives Baseline kidney function is a key predictor of post-operative morbidity and mortality. Whether an increased creatinine at the time of surgery, compared to the lowest creatinine in the 3 months prior to surgery, is associated with poor outcomes has not been evaluated. We examined whether creatinine elevations from “baseline” were associated with adverse post-operative outcomes. Methods A total of 1,486 patients who underwent cardiac surgery at the University of Colorado Hospital between January 2011 and May 2016 met inclusion criteria. “Change in creatinine from baseline” was defined as the difference between the immediate pre-surgical creatinine value, and the lowest creatinine value within three months preceding surgery. Outcomes evaluated were in-hospital mortality, post-operative infection, post-operative stroke, development of stage 3 AKI, ICU length of stay, and hospital length of stay. Outcomes were adjusted using a balancing score to account for differences in patient characteristics. Results There were significant increases in the odds of post-operative infection (OR 1.17, CI 1.02-1.34, per 0.1 mg/dL rise in creatinine), stage 3 AKI (OR 1.44, CI 1.18-1.75), ICU LOS (OR 1.13 (1.01-1.26), and hospital LOS (1.09 (1.05-1.13). There was a significant increase in mortality in the unadjusted analysis, although not after adjustement using a balancing score. There was no association with post-operative stroke. Conclusions Elevations in creatinine at the time of surgery above the “baseline” level are associated with increased post-operative morbidity. Baseline creatinine should be established before surgery, and small changes in creatinine should trigger heightened vigilance in the post-operative period.