Long-term Infective Endocarditis Mortality Associated With Injection Opioid Use in the United States: A Modeling Study

Abstract

Background: The expansion of the US opioid epidemic has led to significant increases in infections, such as infective endocarditis (IE), which is tied to injection behaviors. We aimed to estimate the population-level IE mortality rate among people who inject opioids and compare the risk of IE death against the risks of death from other causes.

Methods: We developed a microsimulation model of the natural history of injection opioid use. We defined injection behavior profiles by both injection frequency and injection techniques. We accounted for competing risks of death and populated the model with primary and published data. We modeled cohorts of 1 million individuals with different injection behavior profiles until age 60 years. We combined model-generated estimates with published data to project the total expected number of IE deaths in the United States by 2030.

Results: The probabilities of death from IE by age 60 years for 20-, 30-, and 40-year-old men with high-frequency use with higher infection risk techniques compared to lower risk techniques for IE were 53.8% versus 3.7%, 51.4% versus 3.1%, and 44.5% versus 2.2%, respectively. The predicted population-level attributable fraction of 10-year mortality from IE among all risk groups was 20%. We estimated that approximately 257 800 people are expected to die from IE by 2030.

Conclusions: The expected burden of IE among people who inject opioids in the United States is large. Adopting a harm reduction approach, including through expansion of syringe service programs, to address injection behaviors could have a major impact on decreasing the mortality rate associated with the opioid epidemic.

Keywords: simulation modeling; endocarditis; injection drug use; opioids; serious infections.

Figure 1.

Probability of death, by cause, among (A) women and (B) men who begin injection drug use at age 20. Probability of death beginning at age 20 through age 60 among (A) women and (B) men. Each graph represents a different injection behavior profile. High-frequency use is defined as ≥1 injection/day; low-frequency use is defined as <1 injection/day. Higher infection risk techniques are defined as regularly sharing or reusing injection equipment and not cleaning one’s skin prior to injection; lower infection risk techniques are defined as not regularly sharing or reusing injection equipment and regularly cleaning one’s skin prior to injection. The solid line represents endocarditis mortality; the dotted line represents overdose mortality; the dashed line represents other drug-related mortality (including skin and soft tissue infections).

Figure 2.

Changes in mortality, by cause, among (A) women and (B) men who began injection drug use at age 20 in the sensitivity analysis of pervasive, high-potency opioids (eg, fentanyl). Bar graphs are grouped by injection behavior profile. The first bar in a pair represents the proportion of cause-specific mortality in the base case. The second bar in a pair represents the cause-specific mortality assuming an illicit opioid market that is nearly exclusively fentanyl. The black section represents endocarditis mortality, dark gray represents overdose mortality, light gray represents other drug-related causes, and the lightest gray represents background mortality.

Figure 3.

Changes in mortality, by cause, among (A) women and (B) men who began injection drug use at age 20 in the sensitivity analysis of increased antimicrobial resistant infections. Bar graphs are grouped by injection behavior profile. The first bar in a pair represents the proportion of cause-specific mortality in the base case. The second bar in a pair represents the cause-specific mortality assuming an increase in infections caused by antimicrobial resistance organisms. The black section represents endocarditis mortality, dark gray represents overdose mortality, light gray represents other drug-related causes, and the lightest gray represents background mortality.