Keele Research Repository

Background
Unplanned hospital readmissions are an important quality metric for benchmarking but there is limited data following an acute myocardial infarction (AMI). This study aims to examine the 30-day unplanned readmission rate, predictors, causes and outcomes after hospitalization for AMI.

Methods
The U.S. Nationwide Readmission Database was utilized to analyze patients with a primary diagnosis of AMI between 2010-2014. Rates of readmissions, causes and costs were determined and multiple logistic regressions were used to identify predictors of readmissions.

Results: Of 2,204,104 patients with AMI the 30-day unplanned readmission rate was 12.3%(n=270,510), which changed from 13.0%-11.5% between 2010-2014. The estimated impact of readmissions in AMI was ~694 million USD and ~279,000 additional bed days per year. Comorbidities such as diabetes (OR 1.27 95%CI 1.25-1.29), chronic lung disease (OR 1.29 95%CI 1.26-1.31), renal failure (OR 1.38 95%CI 1.35-1.40) and cancer (OR 1.35 95%CI 1.30-1.41) were independently associated with unplanned readmission. Discharge against medical advice was the variable most strongly associated with unplanned readmission (OR 2.40 95%CI 2.27-2.54). Non-cardiac causes for readmissions accounted for 52.9% of all readmissions. The most common cause of cardiac readmission was heart failure (14.3%) and for non-cardiac readmissions was infections (8.8%).

Conclusions: Readmissions during the first month after AMI occur in more than 1 in 10 patients resulting in a healthcare cost of ~694 million USD per year and ~279,000 additional bed days per year. These finding have important public health implications. Strategies to identify and reduce readmissions in AMI will dramatically reduce health care costs for society.