Unplanned hospital readmissions after acute myocardial infarction: a nationwide analysis of rates, trends, predictors and causes in the United States between 2010 and 2014

BACKGROUND: Unplanned hospital readmissions are an important quality metric for benchmarking, but there are 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 USA Nationwide Readmission Database was utilized to analyze patients with a primary diagnosis of AMI between 2010 and 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 to 11.5% between 2010 and 2014. The estimated impact of readmissions in AMI was ~718 million USD and ~281000 additional bed days per year. Comorbidities such as diabetes [odds ratio (OR) 1.27, 95% confidence interval (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). Noncardiac causes for readmissions accounted for 52.9% of all readmissions. The most common cause of cardiac readmission was heart failure (14.3%) and for noncardiac readmissions was infections (8.8%). CONCLUSION: Readmissions during the first month after AMI occur in more than one in 10 patients resulting in a healthcare cost of ~718 million USD per year and ~281000 additional bed days per year. These findings have important public health implications. Strategies to identify and reduce readmissions in AMI will dramatically reduce healthcare costs for society.