Published reports indicate that as many as 8% of cardiac surgical patients are readmitted to a cardiovascular intensive care unit (CVICU) during the same hospital stay, with readmission associated with significantly increased risk of morbidity and mortality. Having previously derived and internally validated a CVICU readmission risk score in more than 10,000 patients using variables spanning the entire peri-operative period (including post-operative complications) that showed good model performance but lacked prospective validation, Sean van Diepen, MD, MSc, and colleagues conducted a study to do just that.

For the study, published in the Journal of Critical Care, the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) CVICU readmission score was calculated at surgical ward discharge among a prospective consecutive cohort of 805 adult patients admitted to the CVICU following CABG and/or valvular surgery. The study compared observed versus predicted CVICU readmission and evaluated model discrimination. In addition, model performance was tested when six pre-specified respiratory (re-intubation, tracheostomy, oxygen at discharge) and hemodynamic variables (heart rate, systolic blood pressure, inotropes at discharge) were added.

Among study participants, 4.6% were readmitted to the CVICU, and among them, median CVICU length of stay (9.0 vs 2.0 days) and all-cause, in-hospital mortality rates (8.1% vs 0.4%) were higher when compared with non-readmitted patients. The key findings, however, according to Dr. van Diepen, “are that in a prospective cohort, the model had good discrimination (c-index=0.748) and the addition of systolic blood pressure at discharge yielded the largest improvement in model discrimination (c-index=0.782; Hosmer-Lemshow p=0.749).”

Dr. van Diepen notes that future research in this area should focus on evaluating wither the APPROACH CVICU score can be operationalized in quality-improvement studies designed to identify higher-risk patients and implement teach-based, post-discharge readmission risk interventions. In the meantime, he believes the current data “show that the APPRAOCH CVICU risk score has good model performance and can potentially be used in clinical practice to stratify readmission risk in patients undergoing CABG and/or valvular surgery.”