Analysis of U.S. real-world data shows the newer antiviral baloxavir is linked to fewer flu-related hospital stays than oseltamivir, offering fresh insight into how outpatient influenza care may reduce downstream healthcare burden.
Study: Comparison of clinical outcomes of oseltamivir versus baloxavir in outpatients with influenza: a retrospective cohort analysis. Image credit: Subbotina Anna/Shutterstock.com
A new study published in the International Journal of Infectious Diseases reports that antiviral medicine baloxavir is associated with higher efficacy than oseltamivir in reducing the rates of hospitalization and emergency department visits in patients with influenza infection.
Why influenza complications still strain healthcare systems
Influenza is a common respiratory infection caused by influenza viruses. In most cases, the infection remains mild and resolves without treatment. However, the infection can cause serious complications in elderly people aged 65 years and above, children younger than five years, people with comorbid respiratory or cardiovascular disease, obese people, and pregnant women.
Seasonal influenza viruses cause approximately 1 billion infections per year, resulting in 3 to 5 million cases of severe illness. About 290,000 to 650,000 deaths occur every year due to these infections worldwide. In the United States, influenza accounts for an estimated 10,000 to 40,000 deaths, nearly 200,000 hospitalizations, and millions of days lost from work each year.
Timely administration of antiviral treatment is the key to preventing complications in people with severe influenza infection. The main drugs used in clinical settings to treat influenza are neuraminidase inhibitors and cap-dependent endonuclease inhibitors.
Neuraminidase is a viral surface glycoprotein that plays a crucial role in the survival and transmission of influenza viruses. Neuraminidase inhibitors have been used for antiviral treatment for many years, with oseltamivir being the most frequently used globally.
Cap-dependent endonuclease (CEN) is an enzyme that plays a role in mRNA synthesis in certain viruses, including influenza viruses. CEN inhibitors such as baloxavir marboxil block this enzyme to prevent viral replication. Baloxavir marboxil is a relatively new medicine that received approval from the U.S. Food and Drug Administration (FDA) on October 24, 2018.
In the current study, researchers from Shin-Kong Wu Ho-Su Memorial Hospital and National Taipei University of Nursing and Health Sciences, Taiwan, conducted a real-world comparative effectiveness analysis to evaluate the antiviral efficacy of oseltamivir and baloxavir marboxil among influenza outpatients in controlling the rates of hospitalization, emergency department visits, and mortality among outpatients with influenza.
Comparing two antiviral drugs
The study included 73,899 influenza outpatients treated with oseltamivir and 1,592 patients treated with baloxavir. Participants’ clinical outcome data were derived from the TriNetX US Collaborative Network, which comprises 69 healthcare organizations and includes patients recorded between January 2016 and December 2023.
Key clinical outcomes analyzed in the study included all-cause mortality, all-cause hospitalization, and emergency department visits. These outcomes were assessed at one month, three months, and six months after the index date to evaluate the short-term, intermediate-term, and long-term health events experienced by patients with influenza; the index date referred to the date of initial prescription for either oseltamivir or baloxavir.
Baloxavir linked to fewer hospitalizations
The study analysis revealed that the treatment with baloxavir was associated with significantly lower rates of hospitalization and emergency department visits compared to the treatment with oseltamivir. Baloxavir treatment was also associated with lower overall emergency department visit rates, reaching statistical significance at the six-month follow-up, while both treatments exhibited similar mortality rates.
The rates of hospitalization and emergency department visits in the oseltamivir-treated group remained significantly higher than those in the baloxavir-treated group in the short-term (one month), intermediate-term (three months), and long-term (six months) periods.
The observed beneficial outcomes related to baloxavir treatment were more pronounced among female patients and those under 50 years of age. However, treatment-related differences were less consistent among patients aged 50 years or older, with no clear advantage observed for emergency department visit outcomes in this age group.
Suggestions for flu treatment choices
The study provides real-world evidence on the therapeutic efficacy of baloxavir and oseltamivir in managing influenza. According to the findings, baloxavir was associated with greater reductions in rates of hospitalization compared to oseltamivir among influenza outpatients over a six-month follow-up period, with more modest and time-dependent differences observed for emergency department visits.
The study found no significant differences in mortality rates between the two treatment groups, which may be due to the relatively small number of baloxavir users compared to oseltamivir users included in the study population.
Overall, the study findings suggest that baloxavir may provide clinical advantages over oseltamivir in reducing complications that necessitate further healthcare treatment. Although these findings are broadly consistent with previous real-world studies and clinical trials, some randomized controlled trials have linked baloxavir treatment to faster viral clearance, with only modest clinical benefits. Such discrepancies indicate variations in therapeutic outcomes across populations and clinical endpoints.
The study primarily included White patients, which may limit the generalizability of its findings to other racial or ethnic groups. Future studies should include diverse populations, patient-reported outcomes, and pharmacoeconomic analyses to validate these findings in real-world settings further.
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