People who inject drugs and have infective endocarditis have a high risk of recurrent infective endocarditis and death. We aimed to characterize clinical factors associated with mortality and assess the probability of infective endocarditis recurrence in the presence of death as a competing risk.

A retrospective cohort study was conducted of people who inject drugs, identified between April 5, 2007 and March 15, 2018 with the Modified Duke Criteria for definite infective endocarditis. Fine-Gray sub-distribution and Cox proportional hazards modeling were conducted to determine variables associated with the rate of infective endocarditis recurrence and mortality, respectively.

Of the 310 patients with infective endocarditis who inject drugs, 236 experienced a single episode and 74 experienced recurrent episodes. Peripherally inserted central catheter misuse was associated with an increased rate of infective endocarditis recurrence (sub-distribution hazard ratio 2.41; 95% confidence interval [CI], 1.17-4.98; P = .02) and mortality (hazard ratio [HR] 2.44; 95% CI, 1.15-5.17; P = .02). Non-right-sided infection, peripheral intravenous therapy, and intensive care unit admission were also associated with increased mortality. Oral therapy (HR 0.38; 95% CI, 0.16-0.91; P = .03), outpatient treatment (HR 0.39; 95% CI, 0.19-0.82; P = .01), and inpatient referral to addiction services (HR 0.39; 95% CI, 0.22-0.70; P = .002) were associated with a decrease in mortality.

Patients who misuse their peripherally inserted central catheter are at higher risk of recurrent infective endocarditis and death. Avoidance of peripherally inserted central catheter lines and use of intravenous peripheral therapy did not reduce mortality, but oral therapy was associated with reduced risk. Inpatient addiction services referral is important.