702. Characteristics of Infective Endocarditis (IE) and Predictors of 90-day Mortality Among People Who Do and Do Not Inject Drugs with IE in Seattle, Washington

Abstract

Background: People who inject drugs (PWID) are at high risk for IE and account for a growing proportion of IE cases in the United States. We describe key characteristics of IE and predictors of 90-day mortality among people who do and do not inject drug at two large academic medical centers. Methods: We used a string-searching and pattern-matching algorithm within all discharge (DC) summaries to query the electronic medical record (EMR) for cases of IE among adults ≥18 years of age at two academic medical centers in Seattle, Washington from December 1, 2013 to July 31, 2019. All cases were chart reviewed by a member of the study team to confirm a clinical diagnosis of IE and verify housing and PWID status, the latter defined as any injection drug use in the 3 months prior to admission. Microbiology and valve involvement were extracted from DC summaries and chart-reviewed where needed. Deaths were obtained from Washington state death index, which links to our EMR. Descriptive statistics were used to compare PWID and non-PWID with IE, and Kaplan-Meier log rank tests and Cox proportional hazard models were used to assess for predictors of 90-day mortality. Results: We identified 387 patients with IE, 44% (n=166) of whom were PWID. When compared to non-PWID, PWID were younger (median age 33 vs. 55 years, p< 0.001) and more likely to be female (48% vs. 31%, p=0.001), homeless (41% vs. 9%, p< 0.001), have coagulase-positive Staphylococcal IE (69% vs. 32%, p< 0.001), and have right sided IE (66% vs. 26%, p< 0.001). Seventeen percent (n=64) of patients died within 90 days of admission, including 14% (n=23) of PWID and 19% (n=41) of non-PWID, with no difference in 90-day mortality between these groups (log-rank p=0.3). In univariate analyses, having left sided IE was the only predictor of 90-day mortality (HR 4.79, 95% CI 2.18 - 10.5). Conclusion: Despite PWID being significantly younger and having a much higher frequency of right sided IE, they had similar 90-day mortality to non-PWID in this contemporary, urban cohort of hospitalized IE patients.