Endocarditis is a potentially fatal bacterial infection of the heart valves that is most commonly diagnosed in older patients and those with prior cardiac surgery. “Recent data show that the rate of endocarditis has increased among young men and women with injection drug use behaviors, opioid use disorder, and/or hepatitis C virus (HCV) infection,” says Karen W. Hoover, MD, MPH. As injection drug use has risen over the past two decades among younger people, it has become increasingly important to understand trends in endocarditis because of its associated mortality, morbidity, and cost burden.

For a study published in Clinical Infectious Diseases, Dr. Hoover and colleagues estimated national trends in endocarditis among people with HIV, HCV infection, opioid use disorder, or a substance use disorder other than opioid use disorder. Using commercial and Medicaid health insurance databases, the researchers estimated incident cases of endocarditis in the United States in 2017 and stratified data by HIV, HCV infection, and opioid use disorder. The study group also estimated annual percentage changes (EAPC) in endocarditis from 2007 to 2017 among people with commercial insurance.

Key Findings

According to the analysis, the weighted incidence rate of endocarditis increased slightly over the 11-year time period of the study. The incidence of endocarditis among people with HIV decreased from 2007 to 2017, with an EAPC of -4.3%. However, the incidence increased among those with HCV infection from 2007 to 2017, with an EAPC of 3.2%. The incidence also increased among people with opioid use disorder, with an EAPC of 5.7% over the study period.

Some groups in the study had markedly higher rates, including people aged 18 to 29 years, those who resided in rural locations, persons with HCV infection, and individuals with diagnoses that might indicate opioid use disorder. “Endocarditis is a very rare infection in young persons, but our data demonstrated a notably large increase in endocarditis among individuals with HCV infection or opioid use disorder,” says Dr. Hoover (Figure). “These increases mirror the growing opioid crisis in the U.S. Our study highlights that endocarditis, a serious and potentially deadly complication, is associated with injection drug use behaviors.”

Critical Implications

Findings from the study underscore the importance of primary prevention for endocarditis. “This is an infection that causes significant morbidity and mortality, and treatment is expensive,” explains Dr. Hoover. “Interventions for harm reduction in the opioid crisis have focused primarily on preventing overdose deaths and HIV and HCV infection. However, it is also important to implement prevention efforts that focus on endocarditis as a possible result from sharing injection equipment or from injecting skin that has not been disinfected.”

Physicians should be aware of the risk of endocarditis in people who inject drugs and counsel their patients with opioid use disorder or HCV infection on strategies for preventing the infection, according to Dr. Hoover. “This includes education on the importance of not sharing injection equipment and using good injection hygiene practices,” she says. “In addition, referring patients who report injection drug use behaviors to harm reduction services may help prevent HIV and HCV transmission; prevent endocarditis among people who inject drugs; and reduce risk for overdose deaths. These are important opportunities to connect people to medications for opioid use disorder and regular testing for infections.”

Future Research

The study sheds light on the seriousness of endocarditis and its association with injection drug use behaviors, but more studies are needed. “Future research should evaluate outcomes related to endocarditis in young people,” Dr. Hoover says. “This includes assessing the rate of reinfection in young persons with endocarditis who continue to inject drugs, stroke, surgical valve treatment, and mortality after treatment of endocarditis. Studies are also needed to examine costs associated with the diagnosis and treatment of endocarditis in young persons and to gain a better understanding of patient awareness of the link between endocarditis and injection drug use behaviors. Interventions and educational campaigns should be developed, implemented, evaluated, and scaled-up accordingly to prevent endocarditis related to injection drug use.”