Predicting acute kidney injury after cardiac surgery: a systematic review

Acute kidney injury (AKI) after cardiac surgery confers a significant increased risk of death. Several risk models have been developed to predict postoperative kidney failure after cardiac surgery. This systematic review evaluated the available risk models for AKI after cardiac surgery. Literature searches were performed in the Web of Science/Knowledge, Scopus, and MEDLINE databases for articles reporting the primary development of a risk model and articles reporting validation of existing risk models for AKI after cardiac surgery. Data on model variables, internal or external validation (or both), measures of discrimination, and measures of calibration were extracted. The systematic review included 7 articles with a primary development of a prediction score for AKI after cardiac surgery and 8 articles with external validation of established models. The models for AKI requiring dialysis are the most robust and externally validated. Among the prediction rules for AKI requiring dialysis after cardiac surgery, the Cleveland Clinic model has been the most widely tested thus far and has shown high discrimination in most of the tested populations. A validated score to predict AKI not requiring dialysis is lacking. Further studies are required to develop risk models to predict milder AKI not requiring dialysis after cardiac surgery. Standardizing risk factor and AKI definitions will facilitate the development and validation of risk models predicting AKI.