Nephrocheck for Prediction of In-Hospital Acute Kidney Injury and Major Adverse Kidney Events After Cardiac Surgery

Acute kidney injury (AKI) is a common complication after cardiac surgery and is a risk factor for long-term major adverse kidney events (MAKE). This study aimed to evaluate the association between postoperative Nephrocheck AKI risk score with postoperative in-hospital AKI and MAKE up to 5 years after cardiac surgery.

The study included 610 patients who underwent nonemergent cardiac surgery with cardiopulmonary bypass (CPB). The Nephrocheck AKI risk score 6 hours after CPB was evaluated for association with AKI. The peak Nephrocheck AKI risk score that occurred between 6 hours post-CPB and postoperative day 4 was evaluated for association with MAKE. NephroCheck values were log2-transformed and mean-centered. Logistic and Cox regression were used to assess associations with AKI and MAKE, respectively. Models included linear terms and quadratic and cubic terms to evaluate nonlinearity. Optimal thresholds were derived using receiver operating characteristic (ROC) analysis and the Youden index.

The incidence of postoperative all-stage in-hospital AKI was 110/610 (18.0%), and the incidence of MAKE was 257/610 (42.1%). For AKI, higher-order terms were not significant; therefore, linear models were retained. Each twofold increase in the 6-hour biomarker concentration was associated with increased odds of AKI in unadjusted (OR 1.49; 95% confidence interval [CI], 1.27-1.75; P < .001) and adjusted models (OR range 1.39-1.42; P < .001). An ROC-derived threshold >0.14 was associated with higher odds of AKI in unadjusted (OR 2.43; 95% CI, 1.60-3.69; P < .001) and adjusted models (OR range 2.28-2.34; P < .001). For MAKE, a nonlinear association was observed. The linear term was not significant, whereas the quadratic term was significant in both unadjusted (HR 1.09; 95% CI, 1.04-1.13; P < .001) and adjusted models (HR range 1.06-1.07; P < .008), indicating that the risk of MAKE increases disproportionately at higher peak NephroCheck concentrations. The cubic term was not significant. Patients with peak Nephrocheck AKI risk score >1.69 units had a higher risk of MAKE in unadjusted (HR 2.11; 95% CI, 1.55-2.85; P < .001) and adjusted models (HR range 1.75-2.04; P < .001).

Nephrocheck AKI risk score 6 hours post-CPB was significantly associated with in-hospital postoperative AKI. Peak postoperative NephroCheck measurements were also significantly associated with MAKE up to 5 years after cardiac surgery.