“Multiple clinical studies, including three randomized controlled trials, have demonstrated the efficacy of modern oral therapy for infective endocarditis (IE),” Sarah Freling, MD, explains. “Furthermore, the use of IV-only therapy involves the insertion of a plastic catheter into a patient’s large veins for extended periods, leading to various complications, such as blood clots, secondary infections, bleeding, and vein narrowing. The incidence of these harmful events is considerable, ranging from 10% to 50% depending on the study. Nevertheless, there is a persistent reluctance within the medical community to adopt oral transitional therapy for IE.”

This reluctance relates to medical training, in which “doctors are taught that IV therapy is the only acceptable approach” for IE, according to Dr. Freling. Further, results from more recent clinical trials are often dismissed because they “are not representative of patients that individual doctors treat in ‘the real world,’” she continues.

For a study published in Clinical Infectious Diseases, Dr. Freling and colleagues aimed to provide such real-world data for patients with IE who received oral therapy to “showcase the safety and efficacy of oral transitional therapy compared with IV-only therapy,” she says. “Additionally, we sought to highlight that oral therapy is associated with fewer adverse events.”

The multicenter retrospective cohort study included adults with definite or possible IE who were treated with IV-only versus oral transitional therapy at three acute care public hospitals between December 2019 and June 2022. Clinical success at 90 days, which the researchers defined as being alive with no recurrence of bacteremia or treatment-related infectious complications, served as the primary outcome.

Oral Therapy Clinically Effective & Safe

The analysis included 257 patients with IE who received IV therapy alone (n=211) or oral transitional therapy (n=46). Clinical success rates at 90 days were 84.4% in the IV-only therapy arm and 87% in the oral therapy arm, and results were similar at last follow-up (82.0% vs 76.1%).

“We found no significant difference in clinical outcomes at 90 days or last follow-up between the two cohorts,” Dr. Freling says. “The rates of death, recurrence of bacteremia, and emergent complications while on treatment were not different between the oral transitional therapy and IV-only therapy groups, and readmission rates were similar.”

There was also significantly less harm seen among patients in the oral therapy group (Table). “Specifically, the IV-only therapy group had more acute kidney injuries and a significant number of IV-line-related adverse events,” she explains.

Finally, the researchers reported that a similar number of patients in the IV-only versus oral therapy cohorts failed to finish the planned duration of therapy (7.1% vs 6.5%).

Using Oral Therapy in the Real World

Dr. Freling highlighted the inclusion of resistant causative organisms, such as MRSA and vancomycin-resistant Enterococcus, as notable, as many prior studies have not included these. “Our oral cohort had more patients with MRSA than the IV-only cohort, supporting the efficacy and safety of oral therapy for an organism that clinicians historically believe is hard to treat,” she says. “Other populations that are thought to be difficult to treat are patients with prosthetic valves and intracardiac devices, which our study also included and again did not show a difference in clinical outcomes between cohorts.”

The findings support data from published randomized controlled trials showing that the use of oral transitional therapy for IE is safe and effective.

“Through the inclusion of all comorbidities and studying management in a real-world setting with follow-up variability, we have broadened the applicability of the use of oral transitional therapy,” she says. “We hope to see more clinicians, including infectious disease physicians and hospitalists, become comfortable with the use of oral antimicrobials for the treatment of IE when the patient is stable enough to transition. We also hope that clinicians recognize the benefits and the appropriateness of earlier transition to oral therapy, which many times is prior to hospital discharge.”