Outpatient Antibiotic Fills and 30-Day Readmission Following Patient-Directed Discharge in Drug Use-Associated Infective Endocarditis in a National Medicaid Cohort

BACKGROUND: Antibiotic strategies for drug use-associated infective endocarditis (DUA-IE) are evolving, but data are limited regarding antibiotic access after patient-directed discharge (PDD). We examined antibiotic fill patterns and 30-day readmission among DUA-IE patients with and without PDD. METHODS: Using national Medicaid data (2016-2022), we identified adults aged 18-64 with new DUA-IE episodes. We measured antibiotic fill rates among patients discharged to non-facility settings. We used a landmark design, requiring readmission-free survival for 3 days after discharge to observe antibiotic fills. We used multivariable logistic regression to assess associations between PDD and antibiotic fill with 30-day readmission, overall and stratified by PDD status. RESULTS: Among 19,808 patients included, 5,519 (27.9%) left via PDD. Compared with non-PDD patients, PDD patients were younger, had fewer comorbidities, and had more polysubstance use. Only 17.1% of PDD patients had an antibiotic fill within 3 days versus 44.2% of non-PDD patients (adjusted odds ratio [aOR] 0.25; 95% CI, 0.20-0.33). PDD was associated with increased readmission (aOR 1.91; 95%CI, 1.65-2.21), while antibiotic fill was associated with reduced readmission (aOR 0.45; 95%CI, 0.40-0.50). In stratified analyses, antibiotic fill was associated with a larger magnitude of readmission reduction among PDD patients (aOR 0.27; 95%CI, 0.21-0.34) than among non-PDD patients (aOR 0.50; 95%CI, 0.46-0.55; p for interaction <.001). CONCLUSIONS: These findings highlight the need for proactive strategies that ensure treatment continuity including planning for potential PDD, bedside medication delivery, and expanded use of oral and long-acting intravenous antibiotics.