BACKGROUND A better prediction of postoperative acute kidney injury (AKI) is worthwhile in patients undergoing coronary artery bypass grafting (CABG) because AKI is associated with high rates of morbidity and mortality. The present study was performed to investigate whether preoperative C-reactive protein (CRP) predicted AKI and the long-term rate of mortality in CABG.

METHODS This retrospective cohort study included 1,656 patients whose high-sensitivity CRPs were measured before CABG at two tertiary referral centers from 2004 to 2010. The odds ratios and hazard ratios for AKI and all-cause mortality were measured according to the tertiles of CRP levels after the adjustment of multiple covariates. The net reclassification improvement and integrated discrimination improvement were calculated to determine whether the addition of CRP to the risk model improves predictive capacity. Patients were followed for 12 years.

RESULTS The prevalence of AKI was increased in the third tertile group (42.7%) compared with in the first tertile group (25.6%). The corresponding odds ratio of AKI and p values were 1.86 (95% confidence interval: 1.39 to 2.49) and <0.001, respectively. Compared with the existing risk model, the addition of CRP improved the predictability with 0.135 of net reclassification improvement (p = 0.005) and 0.084 of integrated discrimination improvement (p < 0.001). There were 474 deaths (28.6%) during follow-up. The third tertile group exhibited a higher hazard ratio for mortality (1.63, 95% confidence interval: 1.27 to 2.08) than the first tertile group. This predictability for mortality remained consistent regardless of the presence of AKI.

CONCLUSIONS Preoperative CRP level is a predictor of postoperative AKI and mortality in patients undergoing CABG.