Examination of a Proposed 30-Day Readmission Risk Score on Discharge Location and Cost.

Background. Readmissions cost an estimated $41 billion in the United States each year. To address this, a single institution recently developed a new risk model predictive of 30-day readmission after adult cardiac surgery. The purpose of this study is to validate and refine this new readmission risk model using a statewide database. Methods. A total of 19,964 patients were analyzed using a statewide Society of Thoracic Surgeons database (2014-2017). The aforementioned multivariate model was replicated (model 1): race, hospital length of stay, chronic lung disease, operation type, and renal failure. Model 2 also included discharge location. Thirty-day readmission risk scores and low-risk (0%-10%), moderate-risk (10%-13%), and high-risk (>= 13%) categories were calculated. Results. The overall 30-day readmission rate was 11.1% with both models 1 and 2 predicting readmission (odds ratio, 1.09; 95% confidence interval, 1.08-1.11 vs odds ratio, 1.10; 95% confidence interval, 1.08-1.11). Statistically significant differences were observed across all risk categories in discharge location and total cost. For models 1 and 2, 86% of low-risk patients were discharged to home vs 66.9% and 42.9% of patients in high-risk groups, respectively (P < .001). The largest increases were observed with a hospice discharge location for both model 1 (from $37,930 to $89,285) and model 2 (from $37,930 to $89,230). Conclusions. Both risk models significantly predicted 30-day readmission in our multiinstitutional dataset, confirming the score is valid and a generalizable quality improvement tool. The addition of discharge location and total cost adds valuable information of the ongoing efforts to identify patients at high risk for readmission. (C) 2020 by The Society of Thoracic Surgeons