Abstract 2329: Multivariate Prediction of Renal Insufficiency Developing After Cardiac Surgery
Background: Renal insufficiency following coronary artery bypass graft (CABG) surgery is associated with increased short-term and long-term mortality. We hypothesized that preoperative patient characteristics could be used to predict the patient-specific risk of developing postoperative renal insufficiency.
Methods: Data was prospectively collected on 11,301 patients in Northern New England who underwent isolated CABG surgery between 2001 and 2005. Based on National Kidney Foundation definitions, moderate renal insufficiency was defined as a GFR <60 mL/min/1.73m2 and severe renal insufficiency (SRI) as a GFR<30. Patients with at least moderate renal insufficiency at baseline were eliminated from the analysis, leaving 8,363 patients who became our study cohort. A prediction model was developed to identify variables that best predicted the risk of developing SRI using multiple logistic regression, and the predictive ability model of the quantified using a bootstrap validated C-Index (Area Under ROC) and Hosmer-Lemeshow statistic.
Results: Three percent of the patients with normal renal function prior to CABG surgery developed SRI (229/8,363). In a multivariate model the preoperative patient characteristics most strongly associated with postoperative SRI included: age, gender, white blood cell count >12,000, prior CABG, congestive heart failure, peripheral vascular disease, diabetes, hypertension, and preoperative intra-aortic balloon pump. The predictive model was significant with chi-square 150.8, p-value < 0.0001. The model discriminated well, ROC 0.72 (95%CI: 0.68 – 0.75). The model was well calibrated according to the Hosmer-Lemeshow test.
Conclusions: We developed a robust prediction rule to assist clinicians in identifying patients with normal, or near normal, preoperative renal function who are at high risk of developing SRI. Physicians may be able to take steps to limit this adverse outcome and its associated increase in morbidity and mortality.