High Morbidity and Mortality Among Patients With Sentinel Admission for Injection Drug Use-Related Infective Endocarditis

BACKGROUND: Hospitalizations for individuals with injection drug use-related infective endocarditis (IDU-IE) represent an increasing portion of all patients with endocarditis. This study describes the evolving trends in demographics, clinical characteristics, rates of surgical intervention, and mortality among patients hospitalized with IE, comparing those with and without injection drug use. METHODS: This is a retrospective cohort study of patients admitted between January 1, 2007 to June 30, 2015 at a tertiary care center in Boston, Massachusetts. Endocarditis was defined by International Classification of Diseases, Ninth Revision code and verified by the modified Duke Criteria for IE. The clinical characteristics, microbiology, site of infection, complications of IE, and outcome were all abstracted by chart review. Rates of surgical consultation and surgical intervention within 90 days of admission were obtained, and assessment of surgical risk calculated was by EuroSCORE II (euroscore.org/calc). Subsequent hospitalizations for all causes were also reviewed. RESULTS: Injection drug use-related infective endocarditis occurred in younger patients with lower rates of diabetes, renal dysfunction, and prior cardiothoracic (CT) surgery than those without IDU. Injection drug use-related infective endocarditis was associated with higher rates of complications, CT surgery consultation, and surgery within 90 days for absolute surgical indication. Readmissions for endocarditis occurred in 20% of IDU-IE patients and 9% of those with non-IDU IE. All-cause 1-year mortality rates were similar (IDU-IE 16%, non-IDU IE 13%; P = .58). CONCLUSIONS: Despite younger age, fewer medical comorbidities, and fewer prior cardiac surgeries, all-cause 1-year mortality was similar for patients after sentinel admission for IDU-IE compared with non-IDU IE. Interventions in the acute hospital setting and after discharge are needed to support patients with IDU-IE, focusing on harm reduction and treatment of addiction to reduce the unexpectedly high mortality of this young population.