Correlates of 90-Day Mortality Among People Who Do and Do Not Inject Drugs With Infective Endocarditis in Seattle, Washington

Background Infective endocarditis (IE) remains highly morbid, but few studies have evaluated factors associated with IE mortality. We examined correlates of 90-day mortality among people who inject drugs (PWID) and people who do not inject drugs (non-PWID). Methods We queried the electronic medical record for cases of IE among adults ≥18 years of age at 2 academic medical centers in Seattle, Washington, from 1 January 2014 to 31 July 2019. Cases were reviewed to confirm a diagnosis of IE and drug use status. Deaths were confirmed through the Washington State death index. Descriptive statistics were used to characterize IE in PWID and non-PWID. Kaplan-Meier log-rank tests and Cox proportional hazard models were used to assess correlates of 90-day mortality. Results We identified 507 patients with IE, 213 (42%) of whom were PWID. Sixteen percent of patients died within 90 days of admission, including 14% of PWID and 17% of non-PWID (P = .50). In a multivariable Cox proportional hazard model, injection drug use was associated with a higher mortality within the first 14 days of admission (adjusted hazard ratio [aHR], 2.33 [95% confidence interval {CI}, 1.16–4.65], P = .02); however, there was no association between injection drug use and mortality between 15 and 90 days of admission (aHR, 0.63 [95% CI, .31–1.30], P = .21). Conclusions Overall 90-day mortality did not differ between PWID and non-PWID with IE, although PWID experienced a higher risk of death within 14 days of admission. These findings suggest that early IE diagnosis and treatment among PWID is critical to improving outcomes.