Preoperative prediction of prolonged stay in the intensive care unit for coronary bypass surgery

Abstract

Objectives: To construct a predictive model for a prolonged stay in the intensive care unit (ICU) for coronary artery bypass graft surgery (CABG).

Methods: Eight hundred and eighty-eight patients undergoing CABG were studied by univariate and multivariate analysis. Prolonged stay in the ICU was defined as >/=3 days stay. Stepwise selective procedure (P</=0.05) was used to identify a subset of variables with prognostic value for prolonged stay. This subset was used to calculate a prognostic score S and predicted probability P (P=1/1+e(-S)). Sensitivity analysis was used for evaluation.

Results: Significant risk factors for prolonged stay in the ICU were: lung disease, no-sinus rhythm, no-mild valve pathology, reoperation, no-elective operation, and no-off-pump procedure. The receiver operating characteristic curve gave an area under the curve value of 0.68 for prolonged stay in ICU. Observed probabilities compared well with the predicted probabilities. Patients were classified into low (5%), intermediate (15%), high (30%), and very high-risk groups (40%). A predicted probability of >/=0.40 was used as cut-off point for the prognostic test. The specificity of this test for prolonged stay in the ICU was 99%; sensitivity 9%; positive predictive value 60%; and negative predictive value 89%.

Conclusions: The results show that individual patients presented for CABG, can be stratified according to their risk for prolonged stay >/=3 days in the ICU.