Readmission to the Intensive Care Unit Following Cardiac Surgery: A Derived and Validated Risk Prediction Model in 4,869 Patients

Abstract

Objective: To derive and validate a clinical risk index that can predict readmission to the intensive care unit (ICU) after cardiac surgery.

Design: Retrospective nonrandomized study to determine the perioperative variables associated with risk of readmission to the ICU after cardiac surgery.

Setting: The study was carried out in a single university hospital.

Participants: This was an analysis of 4,869 consecutive adult patients.

Interventions: All patients underwent cardiac surgery at a single center and were discharged to the ward from the ICU during the index surgical admission.

Measurements and main results: A total of 156 patients (3.2%) were readmitted to the ICU during their index surgical admission. Risk factors associated with readmission were identified by performing univariate analysis followed by multivariate logistic regression. The final multivariable regression model was validated internally by bootstrap replications. Nine independent variables were associated with readmission: urgency of surgery, diabetes, chronic kidney disease stage 3 to 5, aortic valve surgery, European System for Cardiac Operative Risk Evaluation, postoperative anemia, hypertension, preoperative neurological disease, and the Intensive Care National Audit and Research Centre score. Our data also showed mortality (18% v 3.2%, p < 0.0001) was significantly higher in readmitted patients. The median duration of ICU stay (7 [4-17] v 1 [1-2] days, p < 0.0001) and hospital stay (20 [12-33] v 7 [5-10] days, p < 0.0001) were significantly longer in patients who were readmitted to ICU compared to those who were not.

Conclusion: From a comprehensive perioperative dataset, the authors have derived and internally validated a risk index incorporating 9 easily identifiable and routinely collected variables to predict readmission following cardiac surgery.

Keywords: ICU complications; cardiac surgery; logistic regression; readmissions; risk index.