Insurance Status and Quality of Care in Infective Endocarditis: A National Analysis of Disparities in Length of Stay, Discharge, and Mortality

Background: Infective endocarditis (IE) requires 4–6 weeks of intravenous antimicrobial therapy, and timely transition to outpatient parenteral antimicrobial therapy (OPAT) allows clinically stable patients to complete treatment outside the hospital. Because OPAT requires home infusion services or post-acute facility placement that typically depend on coverage, insurance status may strongly influence length of stay (LOS); national data on this association in IE remain limited. Methods: We performed a retrospective cross-sectional analysis of the 2016–2019 National Inpatient Sample (NIS) using ICD-10-CM codes I33 and I38 to identify adult IE hospitalizations. Patients were classified as insured (Medicare, Medicaid, or private insurance) or uninsured (self-pay or no charge). Outcomes included mean and prolonged LOS (>14 and >28 days), in-hospital mortality, discharge against medical advice (AMA), and hospitalization costs. Comparisons used chi-square and Student’s t-tests with appropriate NIS survey weighting. Multivariable Gamma regression (LOS, cost) and logistic regression (binary outcomes) were performed, adjusting for age, sex, race/ethnicity, income quartile, injection drug use (IDU), Elixhauser Comorbidity Index, and hospital characteristics, with an insurance × IDU interaction term. Results: Of 87,211 weighted IE hospitalizations, 81,667 (93.6%) were insured and 5544 (6.4%) were uninsured. Uninsured patients were younger (mean age 40.1 vs. 59.4 years) with lower comorbidity burden but higher injection drug use (IDU) prevalence (38.7% vs. 15.5%). Mean LOS was longer among the uninsured (15.5 vs. 12.4 days, p < 0.001); LOS > 14 days occurred in 35.8% vs. 26.6%, and LOS > 28 days in 18.5% vs. 9.2% (both p < 0.001). AMA discharge was four-fold higher among the uninsured (22.2% vs. 5.5%, p < 0.001), while unadjusted in-hospital mortality was similar (9.0% vs. 9.4%, p = 0.32). LOS and AMA disparities persisted in both IDU and non-IDU subgroups, with a six-fold AMA disparity among non-IDU patients (15.2% vs. 2.5%). Based on multivariable analysis, uninsured status remained independently associated with prolonged LOS > 28 days (adjusted odds ratio [aOR] 1.46, 95% CI 1.30–1.65), AMA discharge (aOR 3.51, 95% CI 3.10–3.97), and—after accounting for age and comorbidity differences—higher in-hospital mortality (aOR 1.25, 95% CI 1.10–1.43). Conclusions: Uninsured adults hospitalized with IE experienced longer stays, markedly higher AMA rates, and—after adjustment for age and comorbidity—higher in-hospital mortality than insured patients. These findings are consistent with nonclinical barriers to discharge—particularly limited OPAT and post-acute care access—and suggest that the younger, less comorbid profile of uninsured patients masks an underlying outcome disparity. The results identify uninsured IE patients as a population that may benefit from alternative care models and policy reforms expanding safe post-acute antimicrobial therapy.