Yin W, Zhou G, Zhou L, et al. - Given the greater value of preoperative risk scores than postprocedure risk scores due to lack of effective treatment for contrast-induced acute kidney injury (CI-AKI), and lack of effective external validation has made it difficult to accurately apply most of the pre-operative risk scores in clinical practice, thus, researchers reviewed as well as confirmed the published preoperative risk scores for CI-AKI. They systematically explored PubMed and EMBASE databases to identify studies of CI-AKI preoperative risk scores and evaluated their calibration as well as discriminatory in a cohort including 2,669 patients receiving coronary angiography or percutaneous coronary intervention from September 2007 to July 2017. Three definitions of CI-AKI were included: CI-AKI broad1, defined as a rise in serum creatinine (Scr) of 44.2 μmol/L or 25%; CI-AKI broad2, a rise in Scr of 44.2 μmol/L or 50%; and CI-AKI-narrow, a rise in Scr of 44.2 μmol/L. The majority of preoperative risk scores were established on the basis of single-center investigations. Most of the preoperative risk scores lacked external validation. Findings revealed low prediction accuracy of all risk scores for CI-AKI broads. Best discrimination and calibration were displayed by the Maioli score when CI-AKI-narrow definition was used.