Readmissions after cardiac surgery: experience of the National Institutes of Health/Canadian Institutes of Health research cardiothoracic surgical trials network

Abstract

Background: Readmissions are a common problem in cardiac surgery. The goal of this study was to examine the frequency, timing, and associated risk factors for readmission after cardiac operations.

Methods: A 10-center cohort study prospectively enrolled 5,158 adult cardiac surgical patients (5,059 included in analysis) to assess risk factors for infection after cardiac operations. Data were also collected on all-cause readmissions occurring within 65 days after the operation. Major outcomes included the readmission rate stratified by procedure type, cause of readmission, length of readmission stay, and discharge disposition after readmission. Multivariable Cox regression was used to determine risk factors for time to first readmission.

Results: The overall rate of readmission was 18.7% (number of readmissions, 945). When stratified by the most common procedure type, readmission rates were isolated coronary artery bypass grafting, 14.9% (n = 248); isolated valve, 18.3% (n = 337); and coronary artery bypass grafting plus valve, 25.0% (n = 169). The three most common causes of first readmission within 30 days were infection (17.1% [n = 115]), arrhythmia (17.1% [n = 115]), and volume overload (13.5% [n = 91]). More first readmissions occurred within 30 days (80.6% [n = 672]) than after 30 days (19.4% [n = 162]), and 50% of patients were readmitted within 22 days from the index operation. The median length of stay during the first readmission was 5 days. Discharge in 15.8% of readmitted patients (n = 128) was to a location other than home. Baseline patient characteristics associated with readmission included female gender, diabetes mellitus on medication, chronic obstructive pulmonary disease, elevated creatinine, lower hemoglobin, and longer operation time. More complex surgical procedures were associated with an increased risk of readmission compared with the coronary artery bypass grafting group.

Conclusions: Nearly 1 of 5 patients who undergo cardiac operations require readmission, an outcome with significant health and economic implications. Management practices to avert in-hospital infections, reduce postoperative arrhythmias, and avoid volume overload offer important targets for quality improvement.