Infective endocarditis is an infection that occurs in the endocardium or heart valves. This condition occurs when infectious bacteria enter the bloodstream. But lately, the incidence of infective endocarditis is increased in injection drug users. This study aims to evaluate the risk of infective endocarditis in injecting drug users who use hydromorphone, an opioid pain reliever.

This population-based, retrospective cohort study included a total of 60,529 adults aged 18-55 years who injected drugs. The estimated exposure to hydromorphone and the subsequent risk of infective endocarditis was analyzed. The primary outcome of the study was the incidence of infective endocarditis.

Out of 60,529 participants, 733 (1.2%) were diagnosed with infective endocarditis. When 32,576 matched patients were analyzed on a population level, 256 cases (1.6%) of infective endocarditis occurred. The patient-level analysis of 3,884 matched patients indicated that the frequency of infective endocarditis was higher among individuals who filled prescriptions for hydromorphone (2.8%) compared with those who filled non-hydromorphone prescriptions. This association was more significant for controlled-release hydromorphone (3.9%) but less for immediate-release hydromorphone (1.8%).

The research concluded that people who injected drugs and received controlled-release hydromorphone were at a higher risk of infective endocarditis, as compared with other opioids.