Development of a practical prediction score for chronic kidney disease after cardiac surgery

Background: Chronic kidney disease (CKD) is a frequent and serious complication of cardiac surgery. This study was designed to establish a scoring system, calculated in the immediate postoperative period, to assess the risk of CKD at 1 yr in patients undergoing cardiac surgery with cardiopulmonary bypass. Methods: We conducted a cohort study including patients with preoperative estimated glomerular filtration rate above 60 ml min-1 (1.73 m)-2 who underwent cardiac surgery with cardiopulmonary bypass. We identified risk factors for de novo CKD at 1 yr using logistic regression. We derived a risk score for CKD, and externally validated this score in a second cohort. Results: The incidence of CKD was 18% and 23% in the derivation and validation cohorts, respectively. We developed a scoring system that included (i) the occurrence of postoperative acute kidney injury according to the Kidney Disease: Improving Global Outcomes criteria, (ii) age older than 65 yr, (iii) preoperative glomerular filtration rate