Predicting cardiac surgery-associated acute kidney injury: The CRATE score.

PURPOSE

Acute kidney injury (AKI) is a frequent complication after cardiac surgery and is associated with increased mortality. The aim was to design a nondialytic AKI score in patients with previously normal renal function undergoing cardiac surgery.

METHODS

Data were collected on 909 patients who underwent cardiac surgery with cardiopulmonary bypass between 2012 and 2014. A total of 810 patients fulfilled the inclusion criteria. Patients were classified as having AKI based on the RIFLE criteria. Postoperative AKI occurred in 137 patients (16.9%). Several parameters were recorded preoperatively, intraoperatively, and at intensive care unit admission, looking for a univariate and multivariate association with AKI risk. A second data set of 741 patients, from 2 different hospitals, was recorded as a validation cohort.

RESULTS

Four independent risk factors were included in the CRATE score: creatinine (odds ratio [OR], 9.66; 95% confidence interval [CI], 4.77-19.56; P < .001), EuroSCORE (OR, 1.40; CI, 1.29-1.52; P < .001), lactate (OR, 1.03; CI, 1.01-1.04; P < .001), and cardiopulmonary bypass time (OR, 1.01; CI, 1.01-1.02; P < .001). The accuracy of the model was good, with an area under the curve of 0.89 (CI, 0.85-0.92). The CRATE score retained good discrimination in validation cohort, with an area under the curve of 0.81 (95% CI, 0.78-0.85).

CONCLUSIONS

CRATE score is an accurate and easy to calculate risk score that uses affordable and widely available variables in the routine care surgical patients.