Predictive Value of the CRP/Albumin Ratio for Acute Kidney Injury and Renal Replacement Therapy in Critically Ill Patients: A Retrospective Observational Study.

Background: Acute kidney injury (AKI) and the need for renal replacement therapy (RRT) are major complications in critically ill patients. The C-reactive protein (CRP)/albumin ratio (CAR) is a readily available biomarker reflecting systemic inflammation and nutritional status, but its predictive value for renal outcomes in the intensive care unit (ICU) remains uncertain.

Aims: To assess whether the CAR measured within the first 12 hours of ICU admission can predict the development of AKI and the need for RRT in critically ill patients.

Methods: This retrospective observational study was conducted in a tertiary intensive care unit and included 204 ICU patients without acute or chronic kidney failure at admission. CRP and albumin levels were measured within 12 hours of ICU admission. Patients with conditions affecting albumin levels were excluded. AKI and RRT development during ICU stay were recorded. Statistical analyses included the Mann-Whitney U test, Chi-square test, receiver operating characteristic (ROC) analysis for diagnostic performance, and multivariate logistic regression for independent predictors.

Results: AKI occurred in 55.9% and RRT was required in 21.6% of patients. Patients requiring RRT had lower albumin levels and higher acute physiology and chronic health evaluation II (APACHE II) and sequential organ failure assessment (SOFA) scores. Although CAR was slightly elevated in patients with AKI or RRT, it was not independently associated with these outcomes (RRT: OR 0.97, AUC 0.575; AKI: OR 1.03, AUC 0.643).

Conclusions: The CRP/albumin ratio was not an independent predictor of AKI or RRT. Its clinical usefulness may improve, when combined with established illness severity scores for renal risk stratification in ICU patients.