Risk Factors, Trends, and Financial Impact for 30-Day Unplanned Readmissions in Patients Admitted With Myocarditis and COVID-19: Insights From the Healthcare Cost and Utilization Project (HCUP) Nationwide Readmission Database.

BACKGROUND

The coronavirus disease 2019 (COVID-19) outbreak was first documented in Wuhan, China, in December 2019. Myocarditis, an inflammatory condition characterized by swelling and thickening of the heart muscle, has been linked to severe COVID-19 cases, contributing to worse clinical outcomes. The SARS-CoV-2 virus enters human cells through angiotensin-converting enzyme 2 (ACE2), and myocardial involvement can result from direct viral invasion, hyperinflammation, and immune-mediated damage. The exact prevalence of myocarditis among COVID-19 patients remains uncertain due to initial diagnostic limitations.

OBJECTIVE

This study aims to evaluate the risk factors, trends, financial impact, and preventive strategies related to 30-day unplanned hospital readmission in patients diagnosed with both myocarditis and COVID-19.

METHODOLOGY

A retrospective analysis was conducted using a nationwide hospital database from 2020. Patients diagnosed with both myocarditis and COVID-19 were identified based on standardized diagnostic coding criteria. Confounding factors were addressed using multivariable logistic regression to adjust for demographics, comorbidities, and hospital characteristics.

RESULTS

After applying inclusion and exclusion criteria, 28,726 patients were included, with 4,896 (17.04%) experiencing hospital readmission within 30 days. Compared to national readmission rates for other cardiovascular conditions, this rate is notably high. The median patient age was 67 years (interquartile range {IQR}: 56-78, p < 0.001). Women accounted for 38.1% of readmitted patients. Medicare was the primary insurer for 60.9% of the total cohort and 61.9% of those readmitted (p < 0.001). The median cost of the initial hospitalization was estimated at USD 56,480.37 (IQR: USD 56,433.13-56,930.00), highlighting the financial burden of these readmissions. Among readmitted patients, the median length of stay was seven days (IQR: 6-7 days). Multivariable logistic regression identified heart failure (adjusted odds ratio {AOR} 2.14, 95% confidence interval {CI}: 1.91-2.41, p < 0.001), chronic kidney disease (AOR 1.87, 95% CI: 1.63-2.14, p < 0.001), and diabetes mellitus (AOR 1.56, 95% CI: 1.38-1.76, p < 0.001) as the most significant comorbidities associated with readmission.

CONCLUSION

Our study found that the readmission rate of patients with COVID-19 and myocarditis was highest between days 7 and 14, with 42.3% of readmissions occurring in this period. This emphasizes the need for close post-discharge monitoring and timely follow-up appointments to reduce adverse outcomes. Additionally, patients with comorbidities such as heart failure, chronic kidney disease, and diabetes mellitus had a significantly higher risk of readmission, necessitating targeted management strategies. The substantial financial burden of readmissions underscores the need for healthcare system interventions to optimize post-discharge care.