Mortality, morbidity, and cardiac surgery in Injection Drug Use (IDU)-associated versus non-IDU infective endocarditis: The need to expand substance use disorder treatment and harm reduction services.

backgroundThe addiction crisis is widespread, and unsafe injection practices among people who inject drugs (PWID) can lead to infective endocarditis.

methodsA retrospective analysis of adult patients with definite or possible infective endocarditis admitted to a tertiary care center in Portland, Maine was performed over three-year period. Our primary objective was to examine differences in demographics, health characteristics, and health service utilization between injection drug use (IDU)-associated infective endocarditis and non-IDU infective endocarditis. The association between IDU and mortality, morbidity (defined as emergency department visits within 3 months of discharge), and cardiac surgery was examined. Bivariate and multivariate analyses were performed. A subgroup descriptive analysis of PWID was also performed to better examine substance use disorder (SUD) characteristics, treatment with medication for opioid use disorder (MOUD) and health service utilization.

resultsOne-hundred and seven patients were included in the study, of which 39.2% (n = 42) had IDU-associated infective endocarditis. PWID were more likely to be homeless, uninsured, and lack a primary care provider. PWID were notably younger and had less documented comorbidities, however had similar in-hospital mortality rates (10% vs. 14%, p = 0.30), ED visits (50% vs. 54%, p = 0.70) and cardiac surgery (33% vs. 26%, p = 0.42) compared to those with non-IDU infective endocarditis. Ninety-day mortality was less among PWID (19.0% vs. 36.9%, p = 0.05). IDU was not associated with morbidity (adjusted odds ratio (AOR) 0.73, 95% CI 0.18-3.36), 90-day mortality (AOR 0.72, 95% CI 0.17-3.01), or cardiac surgery (AOR 0.15, 95% CI 0.03-0.69). Ninety-day mortality among PWID who received MOUD was lower (3% vs 15%, p = 0.45), as were ED visits (10% vs. 41%, p = 0.42) compared to those who did not receive MOUD.

conclusionsOur results highlight existing differences in health characteristics and social determinants of health in people with IDU-associated versus non-IDU infective endocarditis. PWID had less comorbidities and were significantly younger than those with non-IDU infective endocarditis and yet still had similar rates of cardiac surgery, ED visits, and in-hospital mortality. These findings emphasize the need to deliver comprehensive health services, particularly MOUD and other harm reduction services, to this marginalized population.