Outcomes of Infective Endocarditis Hospitalizations Among Adults with Congenital Heart Disease: A Nationwide Study

Background: Due to increased survival for patients with adult congenital heart disease (ACHD), new challenges have emerged, including management of complications such as infective endocarditis (IE).

Methods: Hospital discharges for ACHD patients with IE in patients >=18 years from the National Inpatient Sample were identified between 2001 and 2014. Weighting was used to create national annual estimates indexed to the United States (U.S.) population. Demographic, clinical, microbiologic, and outcome data were compared stratifying by disease complexity and by age groups categorized as 18-44 years, 45-64 years, and 65+ years.

Results: We identified a total of 22,855 estimated discharges for ACHD IE from 2001 to 2014. There was a 256% increase in annualized number of ACHD IE hospitalizations from 0.41/100,000 adults to 1.05/100,000 adults during this time (Figure 1). Average age was 49.4 years; 36.1% were female. Disease complexity varied with 72.2% classified as simple, 21.6% as complex, and 6.2% as unclassified. Mortality rates did not vary significantly between disease complexity groups (p=0.47), ranging from 4.7% to 6.3%. Mortality was higher in the oldest group (7.8%) compared with the youngest age group (4.4%) and the middle age group (5.7%), p<0.001. Mortality did not vary by ACHD complexity when stratified by age group (p>0.40 for all comparisons) and also did not change significantly over the studied time period (p=0.92). Valve surgery was common (29.7% of hospitalizations), with higher rates of valve surgery among simple ACHD (32.1%) than complex (25.1%) and unclassified (17.9%) ACHD, p<0.001.
Within the cohort, 46.9% had governmental insurance while 39.9% had private insurance. Mortality was higher for those with governmental insurance compared to private insurance (7.1% vs. 4.0%, p<0.001). Valve surgery was less utilized among patients with governmental insurance than private insurance (25.5% vs. 32.4%, p<0.001). Most patients were white (63%), with 8% black, 7.1% Hispanic, and 22% other/missing. Mortality was higher for black patients than white patients (8.2% vs. 5.3%, p=0.03); this difference persisted after adjusting for age, gender, and congenital heart disease complexity (p=0.02). No difference in valve surgery utilization was identified by race. Female patients did not have increased mortality, but were less likely to undergo valve surgery than male patients (22.9% vs. 33.6%, p<0.001).
Streptococcus was the most common cause of IE (30.5%), while staphylococcus was the second most common (20.7%). However, mortality associated with staphylococcus was significantly higher than streptococcus (8.2% vs. 3.0%, p<0.001).

Conclusion: An increase in ACHD IE hospitalizations indexed to the U.S. population was identified between 2001 and 2014. Mortality did not vary significantly by disease complexity. Important gender, racial, and insurance disparities were identified, including decreased surgery utilization for female patients and those with governmental insurance as well as increased mortality for black patients and those with governmental insurance.