Clinical Outcomes of Infective Endocarditis in Injection Drug Users.

Background: Rising rates of hospitalization for infective endocarditis (IE) have been increasingly tied to rising injection drug use (IDU) associated with the opioid epidemic.

Objectives: This study analyzed recent trends in IDU-IE hospitalization and characterized outcomes and readmissions for IDU-IE patients.

Methods: The authors evaluated the National Readmissions Database (NRD) for IE cases between January 2010 and September 2015. Patients were stratified by IDU status and surgical versus medical management. Primary outcome was 30-day readmission and cause, with secondary outcomes including mortality, length of stay (LOS), adjusted costs, and 180-day readmission. The Kruskal-Wallis and chi-square tests were used to analyze baseline differences by IDU status. Multivariable regressions were used to analyze mortality, readmissions, LOS, and adjusted costs.

Results: The survey-weighted sample contained 96,344 (77.8%) non-IDU-IE and 27,432 (22.2%) IDU-IE cases. IDU-IE increased from 15.3% to 29.1% of IE cases between 2010 and 2015 (p < 0.001). At index hospitalization, IDU-IE was associated with reduced mortality (6.8% vs. 9.6%; p < 0.001) but not 30-day readmission (23.8% vs. 22.9%; p = 0.077) relative to non-IDU-IE. Medically managed IDU-IE patients had higher LOS (β = 1.36 days; 95% confidence interval [CI]: 0.71 to 2.01), reduced costs (β = -$4,427; 95% CI: -$7,093 to -$1,761), and increased readmission for endocarditis (18.1% vs. 5.6%; p < 0.001), septicemia (14.0% vs. 7.3%; p < 0.001), and drug abuse (4.3% vs. 0.7%; p < 0.001) compared with medically managed non-IDU-IE. Surgically managed IDU-IE patients had increased LOS (β = 4.26 days; 95% CI: 2.73 to 5.80) and readmission for septicemia (15.6% vs. 5.2%; p < 0.001) and drug abuse (7.3% vs. 0.9%; p < 0.001) compared with non-IDU-IE.

Conclusions: The incidence of IDU-IE continues to rise nationally. Given the increased readmission for endocarditis, septicemia, and drug abuse, IDU-IE presents a serious challenge to current management of IE.