Prognostic value of C-reactive protein to albumin ratio for mortality in acute kidney injury

Background Inflammation plays an important role in the development of acute kidney injury (AKI). However, there are few studies exploring the prognostic influence of C-reactive protein to albumin ratio (CAR) among AKI patients. In this study, we investigated whether CAR could be a useful marker to predict the mortality of AKI. Methods A total of 358 AKI patients were extracted from the Medical Information Mart for Intensive Care III (MIMIC III) database. C-reactive protein (CRP) and albumin were measured at ICU admission. The clinical outcome was 365-day mortality. Cox proportional hazards model and Kaplan-Meier survival analysis were conducted to evaluate the association between CAR and outcome. Results Compared with patients in the survival group, nonsurvivors had higher CAR levels. The area under the receiver operating characteristic (ROC) curve of CAR was higher than that of CRP and albumin for mortality (0.64 vs. 0.63, 0.59, respectively). The cut-off point of CAR for mortality was 7.23. In Cox proportional-hazard regression analysis, CAR (hazards ratio (HR) =2.04, 95% confidence interval (CI) =1.47-2.85, p < 0.001 for higher CAR) and Simplified Acute Physiology Score II (HR = 1.02, 95%CI = 1.00-1.03, p = 0.004) were independent predictors of 365-day mortality. Conclusions Our study demonstrated that a higher level of CAR was associated with 365-day mortality in AKI patients.