Improvement in discrimination and in reclassification of the risk of death within 30-days.

After creatinine variation was added to a 30-day mortality prediction model, improvement in discrimination was assessed by the difference in c-indexes and by the Integrated Discrimination Improvement [27], and improvement in reclassification by the category-less Net Reclassification Index [28]. The 30-day mortality model included the length of bypass and requirement for deep hypothermic circulatory arrest in patients under 10 days of age, and included the length of bypass and the Aristotle score [22] in older ones.
afor the purpose of this study, the pRIFLE stage was assessed within 2 days of surgery.
IDI: Integrated Discrimination Improvement; NRI: Net Reclassification Index.