Infective Endocarditis Among Women Who Inject Drugs.

Importance: In the US and Canada, women comprise approximately one-third of people who inject drugs (PWID); however, clinical characteristics and outcomes of injection drug use complications in women are poorly described.

Objective: To identify clinical characteristics and outcomes of infective endocarditis (IE) among women who inject drugs (WWID).

Design, Setting, And Participants: This is a retrospective cohort study of PWID with definite IE (per 2023 Duke-International Society for Cardiovascular Infectious Diseases criteria) admitted from April 5, 2007, to March 15, 2018, at 5 tertiary-care hospitals in London, Ontario, and Regina, Saskatchewan, Canada. Data were analyzed from June 1, 2023, to August 2, 2024. Descriptive analyses were conducted for baseline characteristics at index hospitalization and stratified by sex.

Main Outcomes And Measures: The primary outcome was the difference in 5-year survival between female and male PWID with IE. The secondary outcome was 1-year survival. Multivariable time-dependent Cox proportional hazards regression analyses were conducted for variables of clinical importance to evaluate 5-year mortality.

Results: Of 430 PWID with IE, 220 (51.2%) were women; of 332 non-PWID with IE, 101 (30.4%) were women. WWID with IE were younger than men (median [IQR] age, 31.5 [27.0-38.5] vs 38.5 [31.0-49.0] years), and 11 of 220 (5.0%) were pregnant at index hospitalization, although only 12 of 220 (5.5%) had contraceptive use documented. Women had a larger proportion of right-sided IE than men (158 of 220 women [71.8%] vs 113 of 210 men [53.8%]). WWID living in urban areas had higher mortality than WWID in rural areas (adjusted hazard ratio [aHR], 2.70; 95% CI, 1.15-6.34; P = .02). Overall mortality was lower among PWID referred for substance use disorder counseling in centers with inpatient services compared with centers with only outpatient referrals (aHR, 0.29; 95% CI, 0.17-0.51; P < .001). Overall mortality was lower with right-sided heart disease for both women (aHR, 0.44; 95% CI, 0.27-0.71; P < .001) and men (aHR, 0.22; 95% CI, 0.10-0.50; P < .001) and was higher with congestive heart failure for both women (aHR, 2.32; 95% CI, 1.29-4.18; P = .005) and men (aHR, 1.73; 95% CI, 1.07-2.79; P = .02).

Conclusions And Relevance: In this cohort of PWID with IE, women were overrepresented. Reasons for women's disproportionately high IE incidence need further study. Inpatient substance use disorder services, contraception counseling, and enhanced social support for WWID living in urban areas need to be prioritized.